{{Short description|Communication connector using the USB protocol}} {{Use American English|date=July 2024}} {{Use mdy dates|date=July 2025|cs1-dates=y}} thumb|upright=1.5|Various legacy USB connectors along a centimeter ruler for scale. From left to right: {{Ordered list|Micro-B plug|Proprietary UC-E6 connector used on many older Japanese cameras for both USB and analog AV output|Mini-B plug (inverted)|Standard-A receptacle (inverted; non-compliant because official USB specifications do not allow for extension cables<ref name="USB 2.0 6.4.4">{{cite tech report |date=April 27, 2000 |title=Universal Serial Bus Specification |edition=Revision 2.0 |institution=USB-IF |at=6.4.4 Prohibited Cable Assemblies }}</ref>)|Standard-A plug|Standard-B plug}}
The initial versions of the USB standard specified connectors that were easy to use and that would have high life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of the USB standard gave rise to another family of connectors to permit additional data links. All versions of USB specify cable properties. Version 3.''x'' cables, marketed as ''SuperSpeed'', added a data link; namely, in 2008, USB 3.0 added a full-duplex lane (two twisted pairs of wires for one differential signal of serial data per direction), and in 2014, the USB-C specification added a second full-duplex lane.
USB has always included some capability of providing power to peripheral devices, but the amount of power that can be given has increased over time. The modern specifications are called ''USB Power Delivery'' (''USB-PD'') and allow up to 240 watts. Initially USB 1.0/2.0 provided up to 2.5 W, USB 3.0 provided up to 4.5 W, and subsequent Battery Charging (BC) specifications provided power up to 7.5 W. The modern Power Delivery specifications began with USB PD 1.0 in 2012, providing for power delivery up to 60 watts; PD 2.0 version 1.2 in 2013, along with USB 3.1, up to 100 W; and USB PD 3.1 in 2021 raised the maximum to 240 W. USB has been selected as the charging format for many mobile phones and other peripheral devices and hubs, reducing the proliferation of proprietary chargers. Since USB 3.1 USB-PD is part of the USB standard. The latest PD versions can also provide power to lower power laptops.
A standard USB-C cable is specified for 60 watts and at least of USB 2.0 data capability.
In 2019, USB4, now exclusively based on USB-C, added connection-oriented video and audio interfacing abilities (DisplayPort) and compatibility to Thunderbolt 3+.
== Connectors <span class="anchor" id="connectors"></span>== thumb|upright=1.5|Comparison of nine of the 14 ''legacy'' USB connectors (11 receptacles, 12 plugs) and the single current USB connector, Type-C
Unlike other data buses (such as Ethernet), USB connections are directed; a host device has ''downstream''-facing ports (DFP) that connect to the ''upstream''-facing port (UFP) of hubs or peripheral devices. USB implements a tiered star-like network topology.
Only downstream-facing ports originally provided power by default; this topology was chosen to easily prevent electrical overloads and damaged equipment.
Every legacy USB cable has two distinct ends with mechanically distinct plugs, one Type-A plug (connecting to a downstream-facing port of a host or hub) and one Type-B plug (connecting to the upstream-facing port of a hub or peripheral device). Each format has a plug and receptacle defined for each of the ''A'' and ''B'' ends. A USB cable must have one Type-A plug and one Type-B plug, the exception to this is Micro-A plug to Standard-A receptacle cables which are allowed.<ref name="microspec" /> USB extension cables with one Type-A plug and one Type-A receptacle do exist but these are not compliant with USB standards.<ref name="USB 2.0 6.4.4" />
With the release of Type‑C came transitional cables: a Type‑C plug at one end and a Type-A or a Type-B plug at the other. These transitional cables are still directional, and in such a cable the Type‑C plug is electrically marked as either ''A'' or ''B'' as appropriate to complement the opposite connector. The modern standard is a cable with a Type-C plug on each end; these cables are non-directional, leaving it to the connected devices to negotiate their respective roles. All legacy receptacles are either Type-A or Type-B except the Micro‑AB and (deprecated<ref name="Deprecation of Mini-A and Mini-AB" />) Mini‑AB receptacles. A Type-AB receptacle accepts both Type-A and Type-B plugs, and a device with such a receptacle takes the DFP (host, hub DFP) or UFP (peripheral device, hub UFP) role according to the type of plug attached.
There are three sizes of legacy USB connectors: The original ''Standard'', the ''Mini'' connectors, which were the first attempt to accommodate handheld mobile equipment (now mostly deprecated), and ''Micro'', all of which were superseded in 2014 by Type‑C, which is required for operation modes with two lanes (USB 3.2 1×2 (10 Gbit/s), USB 3.2 2×2 (20 Gbit/s), or any USB4 modes) and allows power up to 240 watts in either direction.
Before USB4, there were five speeds for USB data transfer: Low-Speed, Full-Speed (both USB 1.0 and 1.1), High-Speed (USB 2.0), SuperSpeed (USB 3.0, later designated as ''USB 3.2 Gen 1×1''), and SuperSpeed+ (designated as ''USB 3.1 Gen 2'', later as ''USB 3.2 Gen 2×1'').
Legacy connectors have differing hardware and cabling requirements for the first three generations of the standard (USB 1.''x'', USB 2.0, and USB 3.''x''). USB devices have some choice of implemented modes, and since USB 3.1 the USB release alone does not sufficiently designate implemented modes. Which capabilities a device supports are defined by the device's chipset or included SoC and the OS's supported drivers (therefore one must check the full names of the supported USB operation modes in the device's specification; the printed icons usually do not specify all modes, or precisely enough). In the USB 3 specifications it is recommended that the insulators visible inside Standard‑A SuperSpeed plugs and receptacles be a specific blue color (Pantone 300 C).<ref name="3.1 Legacy Cable and Connector Spec 1.0"> {{cite web |author = <!-- not stated --> |date = September 22, 2017 |title = USB 3.1 Legacy Cable and Connector Specification |version = 1.0 |url = https://www.usb.org/document-library/usb-31-legacy-cable-and-connector-revision-10 |website = USB Implementers Forum |url-status = live |archive-url = https://web.archive.org/web/20190413224110/https://www.usb.org/document-library/usb-31-legacy-cable-and-connector-revision-10 |archive-date = April 13, 2019 |access-date = June 11, 2025 }}</ref> In Standard‑A receptacles with support for the 10 Gbit/s (Gen 2) signaling rate introduced in USB 3.1, some makers instead use a teal blue color, but the standards recommend the same blue for all SuperSpeed-capable Standard‑A receptacles, including those capable of the higher rate.
=== Properties === thumb|Prohibited USB extension cable, plug on the left, receptacle on the right. (USB does not allow extension cables.<ref name="USB 2.0 6.4.4" /> Non-standard cables may work but cannot be presumed reliable.)
The connectors the USB committee specifies support a number of USB's underlying goals, and reflect lessons learned from the many connectors the computer industry has used. The connector mounted on the host or device is called the ''receptacle'', and the connector attached to the cable is called the ''plug''.<ref name="USB 3.0 Spec"> {{cite web |author = <!-- not stated --> |date = June 6, 2011 |title = Universal Serial Bus 3.0 Specification |version = 1.0 |url = http://www.usb.org/developers/docs/documents_archive/usb_30_spec_070113.zip |website = USB Implementers Forum |url-status = dead |archive-url = https://web.archive.org/web/20131230035108/http://www.usb.org/developers/docs/documents_archive/ |archive-date = December 30, 2013 |access-date = April 28, 2019 }}</ref> The USB specification documents also periodically define the term ''male'' to represent the plug, and ''female'' to represent the receptacle.<ref name="USB 2.0 ECN 1">{{cite web |title=USB 2.0 Specification Engineering Change Notice (ECN) #1: Mini-B connector |via=USB.org |date=October 20, 2000 |url=http://www.usb.org/developers/docs/ecn1.pdf |access-date=April 28, 2019 |archive-url=https://web.archive.org/web/20150412121600/http://www.usb.org/developers/docs/ecn1.pdf |archive-date=April 12, 2015 }}</ref>{{clarify|date=April 2024}}
By design, it is difficult to insert a USB plug into its receptacle incorrectly. The USB specification requires that the cable plug and receptacle be marked so the user can recognize the proper orientation.<ref name="USB 3.0 Spec" /> The USB‑C plug, however, is reversible. USB cables and small USB devices are held in place by the gripping force from the receptacle, with no screws, clips, or thumb-turns as other connectors use.
The different A and B plugs prevent accidentally connecting two power sources. However, some of this directed topology is lost with the advent of multi-purpose USB connections (such as USB On-The-Go in smartphones, and USB-powered Wi-Fi routers), which require A-to-A, B-to-B, and sometimes Y/splitter cables. See the USB On-The-Go connectors section below for a more detailed summary description.
There are so-called ''cables'' with A plugs on both ends, which may be valid if the "cable" includes, for example, a USB host-to-host transfer device with two ports.<ref name="cablestogo">{{cite web |title= USB connector guide |url= https://www.cablestogo.com/learning/connector-guides/usb |website=C2G |access-date= December 2, 2013 |url-status= live |archive-url= https://web.archive.org/web/20140421223137/http://www.cablestogo.com/learning/connector-guides/usb |archive-date=April 21, 2014}}</ref> This is, by definition, a device with two logical B ports, each with a captive cable, not a cable with two A ends.
==== Durability ==== The standard connectors were designed to be more robust than many past connectors. This is because USB is hot-swappable, and the connectors would be used more frequently, and perhaps with less care, than previous connectors.
Standard USB connectors have a minimum rated lifetime of 1,500 cycles of insertion and removal,<ref name="usb.org-cabconn" /> and this increased to 5,000 cycles for Mini-B connectors.<ref name="usb.org-cabconn" /> The rating for all Micro connectors is 10,000 cycles,<ref name="usb.org-cabconn">{{cite web |url=http://www.usb.org/developers/devclass_docs/CabConn20.pdf |title=Universal Serial Bus Cables and Connectors Class Document – Revision 2.0 |date=August 2007 |publisher=USB Implementers Forum |archive-url=https://web.archive.org/web/20140611014018/http://www.usb.org/developers/devclass_docs/CabConn20.pdf |archive-date=June 11, 2014}}</ref> and the same applies to USB-C.<ref>{{cite web |author-last=Howse |author-first=Brett |title=USB Type-C Connector Specifications Finalized |url=http://www.anandtech.com/show/8377/usb-typec-connector-specifications-finalized |website=AnandTech |access-date=April 24, 2017 |url-status=dead |archive-url=https://web.archive.org/web/20170318004627/http://www.anandtech.com/show/8377/usb-typec-connector-specifications-finalized |archive-date=March 18, 2017}}</ref> To accomplish this, a locking device was added and a leaf spring was moved from the jack to the plug, so that the most-stressed part is on the cable side of the connection. This change was made so that the connector on the less expensive, and more replaceable, cable would bear the most wear.<ref name="usb.org-cabconn" />{{Page needed |date=January 2024}}
In standard USB, the electrical contacts in a USB connector are protected by an adjacent plastic tongue, and the entire connecting assembly is usually protected by an enclosing metal shell.<ref name="usb.org-cabconn" />
The shell on the plug makes contact with the receptacle before any of the internal pins. The shell is typically grounded, to dissipate static electricity and to shield the wires within the connector.
==== Compatibility ==== The USB standards specify dimensions and tolerances for connectors, to prevent physical incompatibilities, including maximum dimensions of plug bodies and minimum clear spaces around receptacles so that adjacent ports are not blocked.
==== Pin assignments ==== {{See also|USB 3.0#PINOUTS|l1=USB 3.0 § Pin assignments}}
USB 1.0, 1.1, and 2.0 use two wires for power (V<sub>BUS</sub> and GND) and two wires for one differential signal of serial data.<ref>{{Cite web |last=Oji |first=Obi |date=January 2024 |title=ESD and Surge Protection for USB Interfaces – Application Note |url=https://www.ti.com/lit/an/slvaf82b/slvaf82b.pdf |website=Texas Instruments}}</ref> Mini and Micro connectors have five contacts each, rather than the four of Standard connectors, with the additional contact, designated ''ID'', electrically differentiating ''A'' and ''B'' plugs when connecting to the ''AB'' receptacles of On-The-Go devices.<ref>{{cite web |url=http://www.usbpinout.net/ |title=USB Pinout |website=UsbPinout.net |archive-url=https://web.archive.org/web/20140617072910/http://www.usbpinout.net/ |archive-date=June 17, 2014}}</ref> The Type‑C plug of a Type‑C-to-legacy cable or adapter is similarly electronically marked as ''A'' or ''B'': In a cable, it is marked as the complement of the connector on the opposite end because every legacy cable by definition has an ''A'' and a ''B'' end, and in an adapter the Type‑C plug is marked to match the plug the adapter accepts.
USB 3.0 added a (bi-directional) ''lane'' (two additional differential pairs with a total of four wires, SSTx+, SSTx−, SSRx+ and SSRx−), providing full-duplex data transfers at ''SuperSpeed'', making it similar to Serial ATA or single-lane PCI Express.
thumb|left|USB 2 '''Standard, Mini-, and Micro-USB plugs''' shown end-on, not to scale. Light areas represent cavities.<ref name="microspec" /> thumb|Micro-B SuperSpeed plug (shown inverted) {{ordered list |1= Power (V<sub>BUS</sub>, 5 V) |2= Data− (D−) |3= Data+ (D+) |4= ID (On-The-Go) |5= GND |6= SuperSpeed transmit− (SSTx−) |7= SuperSpeed transmit+ (SSTx+) |8= GND |9= SuperSpeed receive− (SSRx−) |10= SuperSpeed receive+ (SSRx+) }}
{| class="wikitable" |+ Standard USB pin assignments |- ! Pin ! Name ! colspan=2 | Wire color{{efn|name="Pin assignments"|In some sources ''D+'' and ''D−'' are erroneously swapped.}} ! Description |- | 1 | V<sub>BUS</sub> |style=background:red;color:white| Red or |style=background:orange; | Orange | +5 V |- | 2 | D− |style=background:white| White or |style=background:gold| Gold | Data− |- | 3 | D+ | colspan=2 style=background:green;color:white| Green | Data+ |- | 4 | GND |style=background:black;color:white| Black or |style=background:blue;color:white| Blue | Ground |}
{| class="wikitable" |+ Mini- and Micro-USB pin assignments |- style="background:#e0e0e0;" ! Pin ! Name ! Wire color{{efn|name="Pin assignments"}} ! Description |- | 1 | V<sub>BUS</sub> |style=background:red;color:white| Red | +5 V |- | 2 | D− |style=background:white| White | Data− |- | 3 | D+ |style=background:green;color:white| Green | Data+ |- | 4 | ID | {{n/a|None (only used in plug)}} | When a cable is connected to a Mini- or Micro-AB receptacle, the ID pin indicates to the On-The-Go device whether the plug is the Type-A (host) or Type-B (peripheral device) end of its cable, causing the device to behave as a host or peripheral accordingly. * Type-A plug (''host'' end): connected to GND * Type-B plug (''peripheral device'' end): not connected |- | 5 | GND |style=background:black;color:white| Black | Signal ground |} {{Notelist|group="Pin assignments"}}
==== Colors ==== thumb|A yellow charge-only "USB" Type-A receptacle and a USB 3.0 Type-A receptacle, both upside-down, on a front panel with card reader
thumb|A blue Standard-A USB receptacle without USB 3.0 contacts fitted
{| class="wikitable" |+ Usual USB color-coding<ref>{{cite web |title=USB Port Colors Explained |url=https://www.corsair.com/us/en/explorer/diy-builder/storage/usb-port-colors-explained/ |website=corsair.com |access-date=26 November 2025 |language=en |date=4 February 2025}}</ref> |- ! colspan="7" | Color ! Location ! Description |- | colspan="6" style="background-color:white; width:5px;" class="mw-no-invert" | | White<br /><small>(required by USB standards)<ref name="Micro-USB 1.01" />{{cn|reason=USB‑IF deletes deprecated specifications, so an archive source of the Mini‑A connector spec is needed|date=June 2025}}</small> | Receptacles and plugs | USB 1.0/1.1: Low-Speed (1.5 Mbit/s) – Full-Speed (12 Mbit/s)<br />Micro‑A, Mini‑A |- | colspan="6" style="background-color:black; width:5px;" class="mw-no-invert" | | Black<br /><small>(required by USB standards)<ref name="Micro-USB 1.01" /><ref name="USB 2.0 ECN 1" /></small> | Receptacles and plugs | USB 2.0: Hi-Speed USB (480 Mbit/s)<br />Micro‑B, Mini‑B |- | colspan="6" style="background-color:grey; width:5px;" class="mw-no-invert" | | Gray<br /><small>(required by USB standards)<ref name="Micro-USB 1.01" />{{cn|reason=USB‑IF deletes deprecated specifications, so an archive source of the Mini‑A connector spec is needed|date=June 2025}}</small> | Receptacles | Micro‑AB, Mini‑AB |- | colspan="6" style="background-color:#005eb8; width:5px;" class="mw-no-invert" | | Blue (Pantone {{nowrap|300 C}})<br /><small>(recommended in USB standards)<ref name="3.1 Legacy Cable and Connector Spec 1.0" /></small> | Receptacles and plugs | Indicates a Standard‑A connector that supports USB 5Gbps (introduced as SuperSpeed in USB 3.0), and possibly USB 10Gbps (introduced in USB 3.1) |- | colspan="6" style="background-color:#6cb0c5; width:5px;" class="mw-no-invert" | | Teal blue<!--See Teal#Teal blue.--><br /><small>(not part of USB standards)</small> | Receptacles and plugs | Indicates a Standard‑A or Standard‑B connector that supports USB 10Gbps (introduced as SuperSpeed+ in USB 3.1) |- | colspan="6" style="background-color:#00C000; width:5px;" class="mw-no-invert" | | Green<br /><small>(not part of USB standards)</small> | Receptacles and plugs | Type‑A or Type‑B, Qualcomm Quick Charge (QC) |- | colspan="6" style="background-color:#800080; width:5px;" class="mw-no-invert" | | Purple<br /><small>(not part of USB standards)</small> | Plugs only | Type‑A or Type‑C, Huawei SuperCharge |- | colspan="3" style="background-color:yellow; width:5px;" class="mw-no-invert" | | colspan="3" style="background-color:red; width:5px;" class="mw-no-invert" | | Yellow or red<br /><small>(not part of USB standards)</small> | Receptacles only |Red: Usually Always On<br /> Yellow: Always On, Passive Power Delivery<br />High-current or sleep-and-charge |- | colspan="6" style="background-color:orange; width:5px;" class="mw-no-invert" | | Orange<br /><small>(not part of USB standards)</small> | Receptacles only | Always On, Passive Power Delivery<br />High-retention connector, mostly used on industrial hardware |}
USB ports and connectors are often color-coded to distinguish their different capabilities and modes. Color coding is only required for the insulators visible inside Micro and Mini connectors: ''A'' connectors are white, ''B'' black, and ''AB'' receptacles, which accept both ''A'' and ''B'' plugs, gray. Pantone 300 C is recommended for USB 3.0 Standard‑A connectors, including those with signalling rate of 5 Gbit/s and 10 Gbit/s, though some manufacturers instead use nonstandard teal for receptacles with signalling rate of 10 Gbit/s.{{r|3.1 Legacy Cable and Connector Spec 1.0|at=§5.3.1.4}}{{r|USB 3.0 Spec|at=§5.3.1.3}}
=== Types === {{multiple image | align = right | total_width = 300 | image1 = USB-A receptacle.webp | caption1 = USB-A receptacle on top and a USB-C receptacle on the bottom | image2 = USB-A.webp | caption2 = USB-A plug connector }} USB connector types multiplied as the specification progressed. The original USB specification detailed Standard-A and Standard-B plugs and receptacles, then referred to as simply ''Type‑A'' and ''Type‑B'', then as other Type‑A and Type‑B connectors were added (first Mini, then Micro), the terms ''Standard‑A'' and ''Standard‑B'' were applied to the original connectors. The ''A''–''B'' distinction is to enforce the directional architecture of USB, with only the host and hubs having Type‑A receptacles and each peripheral device having a Type‑B. The data pins in the standard plugs are recessed compared to the power pins so that power and grounding is established before the data conductors are connected, and the reverse when unplugging. Some devices operate in different modes depending on whether the data connection is made. Charging docks supply power and do not include a host device or data pins, allowing any capable USB device to charge or operate from a standard USB cable. Charging cables provide power connections but not data. In a charge-only cable, the data wires are shorted at the device end; otherwise, the device may reject the charger as unsuitable.
==== Standard connectors <span class="anchor" id="OVERMOLD-BOOT"></span>==== thumb|Pin configuration of Standard‑A and Standard‑B plugs viewed end-on. (Both shapes are inaccurate.) * Standard‑A connectors: This plug has an elongated rectangular cross-section, inserts into a Standard‑A receptacle on a ''downstream facing port'' (DFP) on a USB host or hub, and carries both power and data.<ref>{{Cite web |title=Types of USB Cables: The Ultimate Guide |url=https://www.cdw.com/content/cdw/en/articles/hardware/types-usb-cables.html |access-date=March 20, 2025 |website=CDW.com |language=en}}</ref><ref>{{Cite web |title=Everything You Should Know About USB Types {{!}} USB FAQs |url=https://www.cmd-ltd.com/advice-centre/usb-chargers-and-power-modules/usb-and-power-module-product-help/usb-charger-faqs/ |access-date=March 20, 2025 |website=CMD Ltd |language=en}}</ref> The plug itself is 12mm wide and 4.5mm thick.[https://www.usb.org/sites/default/files/CCWG_A_Plug_Form_Factor_Guideline_Revision_1.0_.pdf] * Standard‑B connectors: This plug has a near square cross-section with the top exterior corners beveled. As part of a removable cable, it inserts into a single ''upstream facing port'' (UFP) on a device, such as a printer. On some devices, the Standard‑B receptacle has no data connections, being used solely for accepting power from the upstream device. This two-connector-type scheme (A–B) prevents a user from accidentally creating a loop.<ref>{{cite journal |author-last=Quinnell |author-first=Richard A. |title=USB: a neat package with a few loose ends |journal=EDN Magazine |publisher=Reed |date=October 24, 1996 |url=http://www.edn.com/design/systems-design/4351549/USB-a-neat-package-with-a-few-loose-end |access-date=February 18, 2013 |url-status=live |archive-url=https://web.archive.org/web/20130523185222/http://www.edn.com/design/systems-design/4351549/USB-a-neat-package-with-a-few-loose-end |archive-date=May 23, 2013}}</ref><ref>{{cite web |title=What is the Difference between USB Type A and USB Type B Plug/Connector? |url=http://digital.ni.com/public.nsf/allkb/0E543C70602423C486256DB8006208DE |url-status=live |archive-url=https://web.archive.org/web/20170207031653/http://digital.ni.com/public.nsf/allkb/0E543C70602423C486256DB8006208DE |archive-date=February 7, 2017}}</ref>
{{Anchor|OVERMOLD-BOOT}} The maximum allowed cross-section of the ''overmold boot'' (which is part of the connector used for its handling) is {{convert|16|by|8|mm|abbr=on}} for the Standard-A plug type, while for the Standard‑B it is {{convert|11.5|by|10.5|mm|abbr=on}}.<ref name="USB 2.0 ECN 1" />
==== Mini connectors ==== thumb|Mini-A (left) and Mini-B (right) plugs thumb|USB Mini-B plug (right) and receptacle (left)
Mini-USB connectors were introduced together with USB 2.0 in April 2000, mostly used with smaller devices such as digital cameras, smartphones, and tablet computers. Both Mini-A and Mini-B plugs are approximately {{convert|3|by|7|mm|abbr=on}}.
The Mini-A connectors and the Mini-AB receptacle were deprecated in May 2007, meaning their use in new products has been prohibited since then.<ref name="Deprecation of Mini-A and Mini-AB">{{cite press release |publisher=USB Implementers Forum |title=Deprecation of the Mini-A and Mini-AB Connectors |date=May 27, 2007 |access-date=January 13, 2009 |url=http://www.usb.org/developers/Deprecation_Announcement_052507.pdf |url-status=dead |archive-url=https://web.archive.org/web/20090306145248/http://www.usb.org/developers/Deprecation_Announcement_052507.pdf |archive-date=March 6, 2009}}</ref> The more common Mini-B connectors are still permitted, but they are not On-The-Go–compliant and cannot be certified;<ref name="Products must use the Micro-AB receptacle"> {{cite web |publisher= USB Implementers Forum |title= Consumer OTG Products must use the Micro-AB receptacle |date= March 2007 |access-date=February 26, 2025 |url=https://compliance.usb.org/index.asp?UpdateFile=OTG&Format=Standard#35 |url-status=live |archive-url=https://web.archive.org/web/20250127060855/https://compliance.usb.org/index.asp?UpdateFile=OTG&Format=Standard |archive-date=January 27, 2025}} </ref><ref name="ID Pin Resistance Increased">{{cite web |publisher=USB IF Compliance Updates |title=ID Pin Resistance on Mini B-plugs and Micro B-plugs Increased to 1 Mohm |date=December 2009 |access-date=March 1, 2010 |url=http://compliance.usb.org/index.asp?UpdateFile=Cables%20and%20Connectors&Format=Standard#63 |url-status=live |archive-url=https://web.archive.org/web/20110720073155/http://compliance.usb.org/index.asp?UpdateFile=Cables%20and%20Connectors&Format=Standard#63 |archive-date=July 20, 2011}}</ref><ref name="Mini Connectors Antiquated"> {{cite web |publisher= USB Implementers Forum |title= Mini Connectors Antiquated |date= March 2021 |access-date=February 26, 2025 |url=https://compliance.usb.org/index.asp?UpdateFile=Cables+and+Connectors&Format=Standard#27 |url-status=live |archive-url=https://web.archive.org/web/20250212045230/https://compliance.usb.org/index.asp?UpdateFile=Cables+and+Connectors&Format=Standard |archive-date=February 12, 2025}} </ref> the Mini-B connector was common for transferring data to and from early smartphones and PDAs, and it appears on devices including the PlayStation Portable and the Motorola Razr V3, where it also acts as a charger on the latter.
The Mini-AB receptacle accepts either the Mini-A or the Mini-B plug, causing the On-The-Go device to behave as a host (A) or peripheral (B) accordingly.
{{Clear}}
==== Micro connectors <span class="anchor" id="MICRO"></span>==== {{Multiple image | total_width=300 | image_gap = 20 | caption_align = center | image1=A Micro-A USB port.jpeg | caption1=Micro-A plug | image2=MicroB USB Plug.jpg | caption2=Micro-B plug }}
Micro-USB connectors, which were announced by the USB-IF on January 4, 2007,<ref name="CabConn20">{{Citation |title=Universal Serial Bus Cables and Connectors Class Document |date=August 2007 |url=http://www.usb.org/developers/docs/devclass_docs/CabConn20.pdf |archive-url=https://web.archive.org/web/20150427001335/http://www.usb.org/developers/docs/devclass_docs/CabConn20.pdf |url-status=dead |version=Revision 2.0 |page=6 |publisher=USB Implementers Forum |access-date=August 17, 2014 |archive-date=April 27, 2015}}</ref><ref>{{cite press release |publisher=USB Implementers Forum |title=Mobile phones to adopt new, smaller USB connector |date=January 4, 2007 |access-date=January 8, 2007 |url=http://www.usb.org/press/pressroom/2007_01_04_usbif.pdf |url-status=live |archive-url=https://web.archive.org/web/20070108050844/http://www.usb.org/press/pressroom/2007_01_04_usbif.pdf |archive-date=January 8, 2007}}</ref> have a similar width to Mini-USB but approximately half the thickness, enabling their integration into thinner portable devices. The Micro-A plug is {{convert|6.85|by|1.80|mm|abbr=on}} with a maximum plug body size of {{convert|11.7|by|8.5|mm|abbr=on}}, while the Micro-B plug has the same height and width with a slightly smaller maximum plug body size of {{convert|10.6|by|8.5|mm|abbr=on}}.<ref name="microspec">{{cite web |url=http://mgvs.org/public/shema/datasheet/usb_20/Micro-USB_final/Micro-USB_1_01.pdf |title=Universal Serial Bus Micro-USB Cables and Connectors Specification |date=April 4, 2007 |publisher=USB Implementers Forum|url-status=live |archive-url=https://web.archive.org/web/20151115224048/http://mgvs.org/public/shema/datasheet/usb_20/Micro-USB_final/Micro-USB_1_01.pdf |archive-date=November 15, 2015 |access-date=January 31, 2015}}</ref>
The thinner Micro-USB connectors were intended to replace the Mini connectors in devices manufactured from May 2007 through late 2014, including smartphones, personal digital assistants, and cameras.<ref name="pinoutguide.com 2012">{{cite web |title=Micro-USB mobile phone/smartphone cable connector pinout diagram |website=pinoutguide.com |date=November 16, 2012 |url=https://pinoutguide.com/CellularPhones-A-N/smartphone_microusb_connector_pinout.shtml |archive-url=https://web.archive.org/web/20240527113809/https://pinoutguide.com/CellularPhones-A-N/smartphone_microusb_connector_pinout.shtml |archive-date=May 27, 2024 |url-status=live |access-date=May 29, 2024}}</ref> [[File:Lightning to USB Micro-B adapter 2.jpg|thumb|An adapter with a Micro‑B receptacle and Lightning plug]] The Micro plug design is rated for at least 10,000 connect–disconnect cycles, which is more than the Mini plug design.<ref name="CabConn20" /><ref name="MicroUSB 1.01">{{cite web |url=http://www.usb.org/developers/docs/usb_20_101111.zip |title=Universal Serial Bus Micro-USB Cables and Connectors Specification to the USB 2.0 Specification, Revision 1.01 |date=April 7, 2007 |access-date=November 18, 2010 |publisher=USB Implementers Forum |format=ZIP |quote=Section 1.3: Additional requirements for a more rugged connector that is durable past 10,000 cycles and still meets the USB 2.0 specification for mechanical and electrical performance was also a consideration. The Mini-USB could not be modified and remain backward compatible to the existing connector as defined in the USB OTG specification. |archive-url=https://web.archive.org/web/20120207112406/http://www.usb.org/developers/docs/usb_20_101111.zip |archive-date=February 7, 2012|url-status=dead}}</ref> The Micro connector is also designed to reduce the mechanical wear on the device; instead, the easier-to-replace cable is designed to bear more of the mechanical wear of connection and disconnection. The ''Universal Serial Bus Micro-USB Cables and Connectors Specification'' details the mechanical characteristics of Micro-A plugs, Micro-AB receptacles (which accept both Micro-A and Micro-B plugs), and Micro-B plugs and receptacles,<ref name="MicroUSB 1.01" /> along with a permitted adapter with a Standard-A receptacle and a Micro-A plug, as would be used e.g. to connect a camera to an existing Standard-A–B cable attached to a desktop printer.
Despite the introduction of the USB-C plug (see below), the Micro-B plug continues to be fitted on certain, often budget, hardware.<ref>{{Cite web |last=Peter |title=Flashback: micro-USB brought order to charging and data transfer cables |url=https://www.gsmarena.com/flashback_microusb_brought_order_to_charging_and_data_transfer_cables-news-47720.php |access-date=March 20, 2025 |website=GSMArena.com |language=en-US}}</ref>
=====OMTP standard===== Micro-USB was endorsed as the standard connector for data and power on mobile devices by the cellular phone carrier group Open Mobile Terminal Platform (OMTP) in 2007.<ref>{{cite web |url=http://www.omtp.org/Publications/Display.aspx?Id=08d2e4e3-ebee-407c-a51b-94057e7f7b19 |title=OMTP Local Connectivity: Data Connectivity |publisher=Open Mobile Terminal Platform |date=September 17, 2007 |access-date=February 11, 2009 |archive-url=https://web.archive.org/web/20081015035350/http://www.omtp.org/Publications/Display.aspx?Id=08d2e4e3-ebee-407c-a51b-94057e7f7b19 |archive-date=October 15, 2008}}</ref>
Micro-USB was embraced as the "Universal Charging Solution" by the International Telecommunication Union (ITU) in October 2009.<ref>{{cite web |publisher=Pressinfo |url=http://www.itu.int/newsroom/press_releases/2009/49.html |type=press release |title=Universal phone charger standard approved—One-size-fits-all solution will dramatically cut waste and GHG emissions |work=ITU |date=October 22, 2009 |access-date=November 4, 2009 |url-status= deviated |archive-url=https://web.archive.org/web/20091105075233/http://www.itu.int/newsroom/press_releases/2009/49.html |archive-date=November 5, 2009}}</ref>
In Europe, Micro-USB became the defined common external power supply (EPS) for use with smartphones sold in the EU,<ref>{{cite web |url=http://europa.eu/rapid/pressReleasesAction.do?reference=IP/10/1776&format=HTML&aged=0&language=EN&guiLanguage=en |title=Commission welcomes new EU standards for common mobile phone charger |work=Press Releases |publisher=Europa |date=December 29, 2010 |access-date=May 22, 2011 |url-status=live |archive-url=https://web.archive.org/web/20110319015833/http://europa.eu/rapid/pressReleasesAction.do?reference=IP%2F10%2F1776&format=HTML&aged=0&language=EN&guiLanguage=en |archive-date=March 19, 2011}}</ref> and 14 of the world's largest mobile phone manufacturers signed the EU's common EPS Memorandum of Understanding (MoU).<ref>{{citation | url = http://europa.eu/rapid/pressReleasesAction.do?reference=IP/10/1776 | title = New EU standards for common mobile phone charger | publisher = Europa | type = press release | url-status = live | archive-url = https://web.archive.org/web/20110103181049/http://europa.eu/rapid/pressReleasesAction.do?reference=IP%2F10%2F1776 | archive-date = January 3, 2011 }}</ref><ref>{{citation | url = http://europa.eu/rapid/pressReleasesAction.do?reference=MEMO/09/301 | archive-url = https://web.archive.org/web/20090704130734/http://europa.eu/rapid/pressReleasesAction.do?reference=MEMO%2F09%2F301 | url-status = live | archive-date = July 4, 2009 | title = The following 10 biggest mobile phone companies have signed the MoU: Apple, LG, Motorola, NEC, Nokia, Qualcomm, Research In Motion, Samsung, Sony Ericsson, Texas Instruments | publisher = Europa | type = press release }}</ref> Apple, one of the original MoU signers, makes Micro-USB adapters available—as permitted in the Common EPS MoU—for its iPhones equipped with Apple's proprietary 30-pin dock connector and, later, Lightning connector.<ref>{{cite news |url=http://gigaom.com/apple/nice-micro-usb-adapter-apple-now-sell-it-everywhere/ |title=Nice Micro-USB Adapter Apple, Now Sell It Everywhere |date=October 5, 2011 |newspaper=Giga om |url-status=live |archive-url=https://web.archive.org/web/20120826101535/http://gigaom.com/apple/nice-micro-usb-adapter-apple-now-sell-it-everywhere/ |archive-date=August 26, 2012}}</ref><ref>{{Citation |url=https://www.engadget.com/2012/11/03/apples-lightning-to-microusb-adapter-in-us/ |title=Apple's Lightning to Micro-USB adapter now available in US, not just Europe anymore |date=November 3, 2012 |newspaper=Engadget |url-status=live |archive-url=https://web.archive.org/web/20170626193154/https://www.engadget.com/2012/11/03/apples-lightning-to-microusb-adapter-in-us/ |archive-date=June 26, 2017}}</ref>
==== USB 3.''x'' connectors and backward compatibility ==== thumb|right|USB 3.0 (marketed as SuperSpeed) Micro-B plug {{See also|USB 3.0#CONNECTORS|l1=USB 3.0 § Connectors}}
USB 3.0 introduced SuperSpeed plugs and receptacles, both Standard and Micro. All 3.0 SuperSpeed receptacles (Standard-A, Standard-B, Micro-B, and Micro-AB) are backward-compatible with the corresponding pre-3.0 plugs; additionally, the Standard-A SuperSpeed plug fits the pre-SuperSpeed Standard-A receptacle. (All other SuperSpeed plugs cannot be attached to pre-SuperSpeed receptacles.)
For any devices to have a SuperSpeed link, all the connectors between them must be Type‑C or SuperSpeed.
Every USB cable predating USB‑C had an ''A'' plug at one end and a ''B'' plug at the other (with the rare exception of one special ''A''–''A'' configuration with certain conductors omitted, for operating system debugging and other host-to-host connection applications).{{r|3.1 Legacy Cable and Connector Spec 1.0|at=§5.5.2}} In a USB‑C-to-legacy cable, the Type‑C plug is electrically marked to take the role complementary to the connector at the opposite end, ''A'' for ''B'' and ''B'' for ''A''. When a modern C–C cable is used, the two connected devices communicate to determine which takes which role.
alt=USB 3.0 Type-B plug|thumb|USB 3.0 (marketed as SuperSpeed) Standard-B plug
==== USB On-The-Go connectors ==== {{Main|USB On-The-Go}}
Before USB‑C, USB On-The-Go (OTG) introduced the concept of a device that could switch roles, performing either the ''host'' role or ''peripheral device'' role, as needed, depending simply on which type of plug was attached. An OTG device was required to have one, and only one, USB connector: a Micro-AB receptacle or, before Micro-USB, a Mini-AB receptacle.
The Micro-AB receptacle is capable of accepting the Micro-A or Micro-B plug of any of the allowed cables and adapters as defined in revision 1.01 of the Micro-USB specification.
Since a Type-AB receptacle allows either an ''A'' or an ''B'' plug to be attached, each corresponding A and B plug design has an ''ID'' contact to indicate electrically whether the plug is the ''A'' or the ''B'' end of its cable: In an ''A'' plug the ID contact is connected to GND, and in a ''B'' plug it is not. Typically, a pull-up resistor in the device is used to detect the presence or absence of the GND connection.
An OTG device with an ''A'' plug inserted is called the ''A-device'' and is responsible for powering the USB interface when required, and by default assumes the role of host. An OTG device with a ''B'' plug inserted is called the ''B-device'' and by default assumes the role of peripheral. If an application on the On-The-Go device requires the role of host, then the Host Negotiation Protocol (HNP) is used to temporarily transfer the host role to the OTG device.
==== USB-C <span class="anchor" id="TYPE-C"></span>==== {{Main|USB-C}}
[[File: USB connector illustration, to scale, front view, Full-Featured Type-C plug.svg |thumb|The USB-C plug]] thumb|A cable with a USB‑C plug, and a USB-C port on a notebook computer
The USB-C connector supersedes all earlier USB connectors, the Mini DisplayPort connector and the Lightning connector since 2025.<ref>{{Cite web |date=September 17, 2023 |title=Apple to complete its USB-C transition for AirPods and other accessories by 2025 |url=https://superchargednews.com/2023/09/17/apple-usb-c-transition-done-2025/ |access-date=September 21, 2023 |language=en-US |archive-date=2025-01-09 |archive-url=https://web.archive.org/web/20250109133551/https://superchargednews.com/2023/09/17/apple-usb-c-transition-done-2025/ |url-status=dead }}</ref> It is used for all USB protocols and for Thunderbolt (3 and later), DisplayPort (1.2 and later), and others. Developed at roughly the same time as the USB 3.1 specification, but distinct from it, the USB-C Specification 1.0 was finalized in August 2014<ref name="Cfinalized" /> and defined a new small reversible connector for all USB and some other devices.<ref name="difference">{{cite web |url=http://www.extremetech.com/computing/197145-reversible-usb-type-c-finally-on-its-way-alongside-usb-3-1s-10gbit-performance |title=USB-C vs. USB 3.1: What's the difference? |website=ExtremeTech |date=March 13, 2015 |access-date=April 9, 2015 |author-last=Hruska |author-first=Joel |url-status=live |archive-url=https://web.archive.org/web/20150411081838/http://www.extremetech.com/computing/197145-reversible-usb-type-c-finally-on-its-way-alongside-usb-3-1s-10gbit-performance |archive-date=April 11, 2015}}</ref> The USB-C plug connects both to hosts and to peripheral devices, as well as to chargers and power supplies, replacing all of the preceding USB connectors with a standard meant to be future-proof.<ref name="Cfinalized">{{cite web |title=USB Type-C Connector Specifications Finalized |url=http://www.anandtech.com/show/8377/usb-typec-connector-specifications-finalized |author-last=Howse |author-first=Brett |date=August 12, 2014 |access-date=December 28, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141228122529/http://www.anandtech.com/show/8377/usb-typec-connector-specifications-finalized |archive-date=December 28, 2014}}</ref><ref name="ngo2014">{{cite web |author-last=Ngo |author-first=Dong |title=USB Type-C: One Cable to Connect Them All|url= https://www.cnet.com/news/usb-type-c-one-cable-to-connect-them-all/ |date=August 22, 2014 |website=c.net |access-date=December 28, 2014 |archive-url=https://web.archive.org/web/20150307064003/http://www.cnet.com/news/usb-type-c-one-cable-to-connect-them-all |archive-date=March 7, 2015}}</ref>
The 24-pin double-sided connector provides four power–ground pairs, two differential pairs for USB 2.0 data (though only one pair is implemented in a USB-C cable), four pairs for SuperSpeed data bus (only two pairs are used in USB 3.1 mode), two "sideband use" pins, V<sub>CONN</sub> +5 V power for active cables, and a configuration pin for cable orientation detection and dedicated biphase mark code (BMC) configuration data channel (CC).<ref name="IDF14-TypeC">{{cite web |url=https://intel.activeevents.com/sf14/connect/sessionDetail.ww?SESSION_ID=1254 |title=Technical Introduction of the New USB Type-C Connector |access-date=December 29, 2014 |archive-url=https://web.archive.org/web/20141229123208/https://intel.activeevents.com/sf14/connect/sessionDetail.ww?SESSION_ID=1254 |archive-date=December 29, 2014}}</ref><ref name="TypeC-DP1.3">{{cite web |title=DisplayPort Alternate Mode for USB Type-C Announced - Video, Power, & Data All Over Type-C |url=http://www.anandtech.com/show/8558/displayport-alternate-mode-for-usb-typec-announced |author-last=Smith |author-first=Ryan |date=September 22, 2014 |website=AnandTech |access-date=December 28, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141218171152/http://www.anandtech.com/show/8558/displayport-alternate-mode-for-usb-typec-announced |archive-date=December 18, 2014}}</ref> Type-A and Type-B adaptors and cables are required for older hosts and devices to plug into USB-C hosts and devices. Adapters and cables with a USB-C receptacle are not allowed.<ref>''Universal Serial Bus Type-C Cable and Connector Specification'' Revision 1.1 (April 3, 2015), section 2.2, page 20</ref> thumb|A USB-C port on a cell phone {{anchor|E-Mark}}A ''Full-Featured'' USB cable is a Type‑C-to-Type‑C cable that supports USB 2.0, USB 3.2 and USB4 data operation, and a ''Full-Featured'' Type‑C receptacle likewise supports the same full set of protocols.<ref name="Type-C Spec 2.4">{{cite web |date = October 2024 |title = Universal Serial Bus Type-C Cable and Connector Specification |version = 2.4 |url = https://usb.org/sites/default/files/USB%20Type-C%202.4%20Release%20202410.zip |website = USB Implementers Forum |url-status = live |archive-url = https://web.archive.org/web/20241221182741/https://usb.org/sites/default/files/USB%20Type-C%202.4%20Release%20202410.zip |archive-date = December 21, 2024 |access-date = February 28, 2025 }}</ref> It contains a full set of wires and is electronically marked (E-marked): It contains an ''E-marker'' chip that responds to the USB Power Delivery ''Discover Identity'' command, a kind of vendor-defined message (VDM) sent over the configuration data channel (CC). Using this command, the cable reports its current capacity, maximum speed, and other parameters.<ref name="USBC22">{{cite tech report |url=https://www.usb.org/document-library/usb-type-cr-cable-and-connector-specification-release-22 |title=Universal Serial Bus Type-C Cable and Connector Specification, Release 2.2 |work=USB Implementers Forum |date=October 2022 |institution=USB 3.0 Promoter Group |access-date=April 12, 2023}}</ref>{{rp|at=§4.9}} Full-Featured USB Type-C devices are a mechanic prerequisite for multi-lane operation (USB 3.2 Gen 1×2, USB 3.2 Gen 2×2, USB4 2×2, USB4 3×2, USB Gen 4 Asymmetric).<ref name="USBC22" />
USB-C devices support power currents of 1.5 A and 3.0 A over the 5 V power bus in addition to baseline 900 mA. These higher currents can be negotiated through the configuration line. Devices can also use the full Power Delivery specification using both BMC-coded configuration line and the legacy BFSK-coded V<sub>BUS</sub> line.<ref name="USBC22" />{{rp|at=§4.6.2.1}} ====Connector dimensions==== {| class="wikitable" summary="The table provides the internal dimensions of USB receptacles.{{cn|date=October 2025}} These measurements represent the opening that accepts the corresponding plug." |+ USB receptacle dimensions (internal opening) |- ! Type ! Width (mm) ! Height (mm) ! Depth (mm) ! Notes |- | Standard-A | 12.35 | 4.5 | 15.2 | Original full-size USB receptacle found on computers and hubs |- | Standard-B | 11.1 | 7.0 | 12.0 | Square-shaped receptacle commonly used on printers and external drives |- | Mini-A | 7.5 | 3.0 | 5.0 | Deprecated smaller receptacle, trapezoidal shape |- | Mini-B | 7.5 | 3.0 | 5.0 | Smaller than Standard, larger than Micro, trapezoidal shape |- | Micro-B | 6.85 | 1.8 | 6.0 | Small receptacle for mobile devices, trapezoidal shape |- | Micro-AB | 6.85 | 1.8 | 6.0 | OTG receptacle that accepts both Micro-A and Micro-B plugs |- | USB-C | 8.34 | 2.56 | 7.5 | Modern reversible receptacle with oval shape |}
These dimensions are for the receptacle openings only and do not include the surrounding plastic or metal housing.{{cn|date=October 2025}}
{| class="wikitable" summary="The table provides the external dimensions of USB plugs.{{cn|date=October 2025}} These measurements represent the portion that inserts into the receptacle. Plug dimensions are precisely controlled to ensure proper fit within receptacle tolerances." |+ USB plug dimensions (external body) |- ! Type ! Width (mm) ! Height (mm) ! Length (mm) ! Notes |- | Standard-A | 11.5 | 4.0 | 14.5 | Original full-size USB plug found on cables |- | Standard-B | 10.5 | 6.5 | 11.5 | Square-shaped plug commonly used on device cables |- | Mini-A | 7.0 | 2.5 | 4.5 | Deprecated smaller plug, trapezoidal shape |- | Mini-B | 7.0 | 2.5 | 4.5 | Smaller than Standard, larger than Micro, trapezoidal shape |- | Micro-A | 6.0 | 1.3 | 5.5 | Small plug for mobile devices, trapezoidal shape |- | Micro-B | 6.0 | 1.3 | 5.5 | Small plug for mobile devices, trapezoidal shape |- | USB-C | 7.9 | 2.1 | 7.0 | Modern reversible plug with oval shape |}
These dimensions are for the plug body only and do not include the cable strain relief or overmold.{{cn|date=October 2025}}
===Compatibilities===
Before the specification of the Type‑C plug, virtually every USB cable had one Type‑A plug at one end and one Type‑B plug at the other end of the cable. The Type‑A plug connects only ''upstream'', either directly to a DFP of the ''host'' or indirectly, by connecting to a DFP of a hub that itself connects, directly or indirectly, to the host. The Type‑B plug connects only ''downstream'', either directly to the single UFP of a peripheral device or to the UFP of a hub to which further hubs and peripheral devices can be connected. An ''On-The-Go'' device has a single Type‑AB port (either Micro‑AB or Mini‑AB) and takes either role according to the plug attached. In a Type‑C–legacy cable, the Type‑C plug is electronically marked to complement the plug at the opposite end: When the legacy plug is a Type‑A, the Type‑C plug is marked as ''B'', and when the legacy plug is a Type‑B, the Type‑C is marked ''A''. A device with a Type‑C receptacle may be capable of taking either role or may only function as one or the other. If a Type‑C plug marked as ''A'' or ''B'' is connected to a device incapable of taking the necessary role, no communication occurs. When two devices, each capable of taking either role, are connected through a Type‑C–Type‑C cable, there is a negotiation to determine which is the ''A'' device and which is the ''B''.
Connectors generally support protocols supported by preceding connector types.
{| class="wikitable" style="max-width:30em; text-align: center;" summary="Table listing each USB plug type and the receptacle types which accept it" |+ USB plug compatibility (and capabilities) ! colspan="4" |Plug ! colspan="4" style="vertical-align: bottom;" |Compatible receptacles |- ! Current ! colspan="2" |USB4 2.0{{efn|name=USB42}} / USB4 / USB 3.2{{efn|name=USB3}} ! style="vertical-align: bottom;" |Type‑C{{efn|name=OtherP}}<br />57px |A Full-Featured Type‑C plug: a smooth metal shell, 8 by 2.5 millimeters, with rounded sides and rounded edges at the facing end. The end has a narrow slot with all contacts inside. The Full-Featured plug has six shield-contact springs, all more prominent than the four in the other Type‑C plugs, and all contacts are present except the center pair on one side. Type‑C plugs only vary in which contacts are present inside; they cannot be distinguished by touch and are difficult to discern by unaided vision. | colspan="4" style="vertical-align: bottom;"|Type‑C<br />57px |A Full-Featured Type‑C receptacle: an opening 8 by 2.5 millimeters with an insulator carrying many contacts floating in the center. (It is also possible for a Type‑C receptacle to simply be the insulator with contacts exposed, with no shell surrounding.) All contacts are present, twelve on each side of the flat insulator. Type‑C plugs only vary in which contacts are present inside so cannot be distinguished by touch. |- ! rowspan="10" |Legacy ! rowspan="4" |USB 3.''x''<br />{{efn|name=Speed31}} ! rowspan="2" |Host (Type‑A) ! style="vertical-align: bottom;" |USB 3.0<br />Standard‑A<br />78px |A USB 3.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the earlier version only in that it has five additional contacts deep inside and that the insulator is either blue ({{nowrap|Pantone 300 C}}) for USB 5Gbps, or teal blue for USB 10Gbps. | colspan="2" style="vertical-align: bottom;" |USB 3.0<br />Standard‑A<br />78px |A USB 3.0 Standard‑A receptacle: a rectangular opening 5 by 12 millimeters with a wide plastic protrusion above the center, the protrusion having notches on its underside for the five electrical contacts added for USB 3.x, or a single notch for the same. | colspan="2" style="vertical-align: bottom;"|USB 2.0<br />Standard‑A{{efn|name=Lim2}}{{efn|name=USB2}}78px |A USB 2.0 Standard‑A receptacle: a rectangular opening 5 by 12 millimeters with a wide plastic protrusion inside above the center. It is distinct from the USB 3.0 variant in that the protrusion lacks the notch or notches on its underside for five additional contacts. |- ! style="vertical-align: bottom;" |USB 3.0<br />Micro‑A{{efn|name=NoMicroA}}<br />76px|A USB 3.0 Micro‑A plug: a wide, flat metal shell, 12 by 2 millimeters, in two sections with latch springs protruding from the bottom side. It is distinct from the USB 3.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side of the wider section are chamfered, and that there may be a raised "A" on the top of the plug body. | colspan="4" style="vertical-align: bottom;"|USB 3.0<br />Micro‑AB{{efn|name=ABrec}}<br />76px|A USB 3.0 Micro‑AB receptacle: an opening 12 by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑B receptacle only in that it has no chamfered corners, where the upper corners of the wider section of the USB 3.0 Micro‑B narrow to preclude insertion of a Type‑A plug |- ! rowspan="2" |Peripheral (Type‑B) ! style="vertical-align: bottom;" |USB 3.0<br />Standard‑B<br />57px|A USB 3.0 Standard‑B plug: 8 millimeters wide by ten high, with an 8-millimeter-wide lower section and a step inward to the 6-millimeter-wide upper section. There is a vertical bump on each side of the wider section, and on the face a wide rectangular opening in the center of the insulator and a smaller open space at the top, bordered by the shell. | colspan="4" style="vertical-align: bottom;"|USB 3.0<br />Standard‑B<br />57px|A USB 3.0 Standard‑B receptacle: an 8-millimeter-square opening with chamfered upper corners and a narrower opening continuing upward 2 millimeters, and a plastic protrusion in the center of the larger section and a smaller plastic protrusion in the narrow section. |- ! style="vertical-align: bottom;" |USB 3.0<br />Micro‑B<br />76px|A USB 3.0 Micro‑B plug: a wide, flat metal shell, 12 by 2 millimeters, in two sections with latch springs protruding from the bottom side. It is distinct from the USB 3.0 Micro‑A plug only in that the edges of the wider section are chamfered on the upper side and that there may a raised "B" on the top of the plug body. | style="vertical-align: bottom;" colspan="2" |USB 3.0<br />Micro‑AB<br />76px|A USB 3.0 Micro‑AB receptacle: an opening 12 by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑B receptacle only in that it has no chamfered corners, where the upper corners of the wider section of the USB 3.0 Micro‑B narrow to preclude insertion of a Type‑A plug | colspan="2" style="vertical-align: bottom;" |USB 3.0<br />Micro‑B<br />76px|A USB 3.0 Micro‑B receptacle: an opening 12 by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑AB receptacle only in that the upper corners of the wider section narrow to preclude insertion of a Type‑A plug |- ! rowspan="6" |USB 2.0 and earlier{{efn|name=USB2}} ! rowspan="3" |Host (Type‑A) ! style="vertical-align: bottom;" |USB 2.0<br />Standard‑A<br />78px|A USB 2.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the later version only in that it lacks five additional contacts deep inside and that the insulator is generally not bright blue. | colspan="2" style="vertical-align: bottom;" |USB 3.0<br />Standard‑A{{efn|name=Lim2}}<br />78px|A USB 3.0 Standard‑A receptacle: a rectangular opening five by twelve millimeters with a plastic protrusion inside near the top, the protrusion having notches for the five electrical contacts added for USB 3.x, or a single notch for the same. | colspan="2" style="vertical-align: bottom;" |USB 2.0<br />Standard‑A<br />78px|A USB 2.0 Standard‑A receptacle: a rectangular opening five by twelve millimeters with a wide plastic protrusion inside above the center. It is distinct from the USB 3.x variant in that the protrusion lacks the notch or notches on its underside for five additional contacts. |- ! style="vertical-align: bottom;" |USB 2.0<br />Micro‑A{{efn|name=NoMicroA}}<br />50px|A USB 2.0 Micro‑A plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side are chamfered, and that there may be a raised "A" on the top of the plug body. | colspan="2" style="vertical-align: bottom;" |USB 3.0<br />Micro‑AB{{efn|name=Lim2}}<br />76px|A USB 3.0 Micro‑AB receptacle: an opening 12 by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑B receptacle only in that it has no chamfered corners, where the upper corners of the wider section of the USB 3.0 Micro‑B narrow to preclude insertion of a Type‑A plug | colspan="2" |USB 2.0<br />Micro‑AB{{efn|name=ABrec}}<br />50px|A USB 2.0 Micro‑AB receptacle: an opening 7 by 2 millimeters, distinct from the USB 2.0 Micro‑B receptacle only in that it is rectangular, where in the Micro‑B receptacle the upper corners narrow to preclude insertion of a Type‑A plug |- ! style="vertical-align: bottom;" |Mini‑A{{efn|name=depc}}<br />50px|A Mini‑A plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑B plug only in that the sides of the wider upper part are flat, where in the Type‑B plug the widest part is only two rounded edges, and that there may be a raised "A" on the top of the plug body. | colspan="2" style="vertical-align: bottom;" |Mini‑AB{{efn|name=depc}}<br />50px|A Mini‑AB receptacle: an opening 7 by 3 millimeters with a gray insulator in the center with the same shape as those of the Mini‑A and ‑B receptacles. The opening of the AB receptacle's opening is the union of those of the A and B receptacles, with only a slight narrowing in the lower half, to allow insertion of either plug type. | colspan="2" style="vertical-align: bottom;" |Mini‑A{{efn|name=depc}}<br />50px|A Mini‑A receptacle: an opening 7 by 3 millimeters with a white insulator in the center with the same shape as those of the Mini‑B and ‑AB receptacles. The A receptacle narrows at the bottom, with little space between the shell and the insulator, to preclude insertion of a B plug. |- ! rowspan="3" | Peripheral (Type‑B) ! style="vertical-align: bottom;" |USB 2.0<br />Standard‑B<br />57px|A USB 2.0 Standard‑B plug: 8 by 7 millimeters, with chamfered upper corners. There is a vertical bump on each side of the shell, and on the face a wide rectangular opening in the center of the insulator. | colspan="2" style="vertical-align: bottom;" |USB 3.0<br />Standard‑B{{efn|name=Lim2}}<br />57px|A USB 3.0 Standard‑B receptacle: an 8-millimeter-square opening with chamfered upper corners and a narrower opening continuing upward 2 millimeters, and a plastic protrusion in the center of the larger section and a smaller plastic protrusion in the narrow section. | colspan="2" style="vertical-align: bottom;" |USB 2.0<br />Standard‑B<br />57px|A USB 2.0 Standard‑B receptacle: an 8-millimeter-square opening with chamfered upper corners and a plastic protrusion in the center. |- ! style="vertical-align: bottom;" |USB 2.0<br />Micro‑B<br />50px|A USB 2.0 Micro‑B plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑A plug only in that the edges of the upper side are chamfered, where in the Type‑A plug all corners are right angles, and that there may be a raised "A" on the top of the plug body. | style="vertical-align: bottom;" |USB 3.0<br />Micro‑AB{{efn|name=Lim2}}{{efn|name=ABrec}}<br />76px|A USB 3.0 Micro‑AB receptacle: an opening 12 by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑B receptacle only in that it has no chamfered corners, where the upper corners of the wider section of the USB 3.0 Micro‑B narrow to preclude insertion of a Type‑A plug | style="vertical-align: bottom;" |USB 3.0<br />Micro‑B{{efn|name=Lim2}}<br />76px|A USB 3.0 Micro‑B receptacle: an opening 12 by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑AB receptacle only in that the upper corners of the wider section narrow to preclude insertion of a Type‑A plug | style="vertical-align: bottom;" |USB 2.0<br />Micro‑AB{{efn|name=ABrec}}<br />50px|A USB 2.0 Micro‑AB receptacle: an opening 7 by 2 millimeters, distinct from the USB 2.0 Micro‑B receptacle only in that it is rectangular, where in the Micro‑B receptacle the upper corners narrow to preclude insertion of a Type‑A plug | style="vertical-align: bottom;" |USB 2.0<br />Micro‑B<br />50px|A USB 2.0 Micro‑B receptacle: an opening 7 by 2 millimeters, distinct from the USB 2.0 Micro‑AB receptacle only in that the upper corners narrow to preclude insertion of a Type‑A plug |- ! style="vertical-align: bottom;" |Mini‑B<br />50px|A Mini‑B plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑A plug only in that the sides of the wider upper part are rounded, where in the Type‑A plug wide part continues downward a bit more providing flat sides, and there may be a raised "B" on the top of the plug body. | colspan="2" style="vertical-align: bottom;" |Mini‑AB{{efn|name=depc}}<br />50px|A Mini‑AB receptacle: an opening 7 by 3 millimeters with a gray insulator in the center with the same shape as those of the Mini‑A and ‑B receptacles. The opening of the AB receptacle's opening is the union of those of the A and B receptacles, with only a slight narrowing in the lower half, to allow insertion of either plug type. | colspan="2" style="vertical-align: bottom;" | Mini‑B<br />50px|A Mini‑B receptacle: an opening 7 by 3 millimeters with a black insulator in the center with the same shape as those of the Mini‑A and ‑AB receptacles. The B is narrower in the lower three-fifths to preclude insertion of a A plug. |}
{| class="wikitable" style="max-width:30em; text-align: center;" summary="Table listing each USB receptacle type and the plug types it accepts" |+ USB receptacle compatibility (and capabilities) ! colspan="4" |Receptacle ! colspan="4" style="vertical-align: bottom;" |Compatible plugs |- ! Current ! colspan="2" |USB4 2.0{{efn|name=USB42}} / USB4 / USB 3.2{{efn|name=USB3}} ! style="vertical-align: bottom;" |Type‑C{{efn|name=OtherP}}<br />center|57px |A Full-Featured Type‑C receptacle: an opening 8 by 2.5 millimeters Fwith an insulator carrying many contacts floating in the center. (It is also possible for a Type‑C receptacle to simply be the insulator with contacts exposed, with no shell surrounding.) All contacts are present, twelve on each side of the flat insulator. Type‑C plugs only vary in which contacts are present inside so cannot be distinguished by touch. | colspan="4" style="vertical-align: bottom;" |Type‑C<br />center|57px |A Full-Featured Type‑C plug: a smooth metal shell, 8 by 2.5 millimeters, with rounded sides and rounded edges at the facing end. The end has a narrow slot with all contacts inside. The Full-Featured plug has six shield-contact springs, all more prominent than the four in the other Type‑C plugs, and all contacts are present except the center pair on one side. Type‑C plugs only vary in which contacts are present inside; they cannot be distinguished by touch and are difficult to discern visually without magnification. |- ! rowspan="11" |Legacy ! rowspan="4" |USB 3.''x''<br />{{efn|name=Speed31}} ! Host (Type‑A) ! style="vertical-align: bottom;" |USB 3.0<br />Standard‑A<br />78px|A USB 3.0 Standard‑A receptacle: a rectangular opening five by twelve millimeters with a wide plastic protrusion above the center, the protrusion having notches on its underside for the five electrical contacts added for USB 3.x, or a single notch for the same. | colspan="2" style="vertical-align: bottom;" |USB 3.0<br />Standard‑A<br />78px|A USB 3.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the earlier version only in that it has five additional contacts deep inside and that the insulator is often bright blue. | colspan="2" style="vertical-align: bottom;" |USB 2.0<br />Standard‑A{{efn|name=Lim2}}<br />78px|A USB 2.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the later version only in that it lacks five additional contacts deep inside and that the insulator is generally not bright blue. |- ! rowspan="2" |Peripheral (Type‑B) ! style="vertical-align: bottom;" |USB 3.0<br />Standard‑B<br />57px|A USB 3.0 Standard‑B receptacle: an 8-millimeter-square opening with chamfered upper corners and a narrower opening continuing upward 2 millimeters, and a plastic protrusion in the center of the larger section and a smaller plastic protrusion in the narrow section. | colspan="2" style="vertical-align: bottom;"|USB 3.0<br />Standard‑B<br />57px|A USB 3.0 Standard‑B plug: 8 by 10 millimeters, with an 8-millimeter-wide lower section and a step inward to the 6-millimeter-wide upper section. There is a vertical bump on each side of the wider section, and on the face a wide rectangular opening in the center of the insulator and a smaller open space at the top, bordered by the shell. | colspan="2" style="vertical-align: bottom;"| USB 2.0<br />Standard‑B{{efn|name=Lim2}}<br />57px|A USB 2.0 Standard‑B plug: 8 by 7 millimeters, with chamfered upper corners. There is a vertical bump on each side of the shell, and on the face a wide rectangular opening in the center of the insulator. |- ! style="vertical-align: bottom;" |USB 3.0<br />Micro‑B<br />76px|A USB 3.0 Micro‑B receptacle: an opening twelve by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑AB receptacle only in that the upper corners of the wider section narrow to preclude insertion of an Type‑A plug | colspan="2" style="vertical-align: bottom;"|USB 3.0<br />Micro‑B<br />76px|A USB 3.0 Micro‑B plug: a wide, flat metal shell, twelve by 2 millimeters, in two sections with latch springs protruding from the bottom side. It is distinct from the USB 3.0 Micro‑A plug only in that the edges of the wider section are chamfered on the upper side and that there may a raised "B" on the top of the plug body. | colspan="2" style="vertical-align: bottom;"|USB 2.0<br />Micro‑B{{efn|name=Lim2}}<br />50px|A USB 2.0 Micro‑B plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑A plug only in that the edges of the upper side are chamfered, where in the Type‑A plug all corners are right angles, and that there may be a raised "A" on the top of the plug body. |- ! On-The-Go (Type‑AB) ! style="vertical-align: bottom;" |USB 3.0<br />Micro‑AB{{efn|name=ABrec}}<br />76px|A USB 3.0 Micro‑AB receptacle: an opening twelve by 2 millimeters, in two sections, distinct from the USB 3.0 Micro‑B receptacle only in that it has no chamfered corners, where the upper corners of the wider section of the USB 3.0 Micro‑B narrow to preclude insertion of an Type‑A plug | style="vertical-align: bottom;" |USB 3.0<br />Micro‑A{{efn|name=NoMicroA}}<br />76px|A USB 3.0 Micro‑A plug: a wide, flat metal shell, twelve by 2 millimeters, in two sections with latch springs protruding from the bottom side. It is distinct from the USB 3.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side of the wider section are chamfered, and that there may be a raised "A" on the top of the plug body. | style="vertical-align: bottom;" |USB 3.0<br />Micro‑B<br />76px|A USB 3.0 Micro‑B plug: a wide, flat metal shell, twelve by 2 millimeters, in two sections with latch springs protruding from the bottom side. It is distinct from the USB 3.0 Micro‑A plug only in that the edges of the wider section are chamfered on the upper side and that there may a raised "B" on the top of the plug body. | style="vertical-align: bottom;" |USB 2.0<br />Micro‑A{{efn|name=NoMicroA}}{{efn|name=Lim2}}<br />50px|A USB 2.0 Micro‑A plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side are chamfered, and that there may be a raised "A" on the top of the plug body. | style="vertical-align: bottom;" |USB 2.0<br />Micro‑B{{efn|name=Lim2}}<br />50px|A USB 2.0 Micro‑B plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑A plug only in that the edges of the upper side are chamfered, where in the Type‑A plug all corners are right angles, and that there may be a raised "A" on the top of the plug body. |- ! rowspan="7" |USB 2.0 and earlier{{efn|name=USB2}} ! rowspan="2" |Host (Type‑A) ! style="vertical-align: bottom;" |USB 2.0<br />Standard‑A<br />78px|A USB 2.0 Standard‑A receptacle: a rectangular opening five by twelve millimeters with a wide plastic protrusion inside above the center. It is distinct from the USB 3.x variant in that the protrusion lacks the notch or notches on its underside for five additional contacts. | style="vertical-align: bottom;" colspan="2" |USB 3.0<br />Standard‑A{{efn|name=Lim2}}<br />78px|A USB 3.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the earlier version only in that it has five additional contacts deep inside and that the insulator is often bright blue. | style="vertical-align: bottom;" colspan="2" |USB 2.0<br />Standard‑A<br />78px|A USB 2.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the later version only in that it lacks five additional contacts deep inside and that the insulator is generally not bright blue. |- ! style="vertical-align: bottom;" |Mini‑A{{efn|name=depc}}<br />50px|A Mini‑A receptacle: an opening 7 by 3 millimeters with a white insulator in the center with the same shape as those of the Mini‑B and ‑AB receptacles. The A receptacle narrows at the bottom, with little space between the shell and the insulator, to preclude insertion of a B plug. | colspan="4" style="vertical-align: bottom;" |Mini‑A{{efn|name=depc}}<br />50px|A Mini‑A plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑B plug only in that the sides of the wider upper part are flat, where in the Type‑B plug the widest part is only two rounded edges, and that there may be a raised "A" on the top of the plug body. |- ! rowspan="3" | Peripheral (Type‑B) ! USB 2.0<br />Standard‑B<br />57px|A USB 2.0 Standard‑B receptacle: an 8-millimeter-square opening with chamfered upper corners and a plastic protrusion in the center. | colspan="4" |USB 2.0<br />Standard‑B<br />57px|A USB 2.0 Standard‑B plug: 8 by 7 millimeters, with chamfered upper corners. There is a vertical bump on each side of the shell, and on the face a wide rectangular opening in the center of the insulator. |- ! USB 2.0<br />Micro‑B<br />50px|A USB 2.0 Micro‑B receptacle: an opening 7 by 2 millimeters, distinct from the USB 2.0 Micro‑AB receptacle only in that the upper corners narrow to preclude insertion of an Type‑A plug | colspan="4" |USB 2.0<br />Micro‑B<br />50px|A USB 2.0 Micro‑B plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑A plug only in that the edges of the upper side are chamfered, where in the Type‑A plug all corners are right angles, and that there may be a raised "A" on the top of the plug body. |- ! Mini‑B<br />50px|A Mini‑B receptacle: an opening 7 by 3 millimeters with a black insulator in the center with the same shape as those of the Mini‑A and ‑AB receptacles. The B is narrower in the lower three-fifths to preclude insertion of an A plug. | colspan="4" |Mini‑B<br />50px|A Mini‑B plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑A plug only in that the sides of the wider upper part are rounded, where in the Type‑A plug wide part continues downward a bit more providing flat sides, and there may be a raised "B" on the top of the plug body. |- ! rowspan="2" | On-The-Go (Type‑AB) ! USB 2.0<br />Micro‑AB{{efn|name=ABrec}}<br />50px|A USB 2.0 Micro‑AB receptacle: an opening 7 by 2 millimeters, distinct from the USB 2.0 Micro‑B receptacle only in that it is rectangular, where in the Micro‑B receptacle the upper corners narrow to preclude insertion of an Type‑A plug | colspan="2" |USB 2.0<br />Micro‑A{{efn|name=NoMicroA}}<br />50px|A USB 2.0 Micro‑A plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side are chamfered, and that there may be a raised "A" on the top of the plug body. | colspan="2" |USB 2.0<br />Micro‑B<br />50px|A USB 2.0 Micro‑B plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑A plug only in that the edges of the upper side are chamfered, where in the Type‑A plug all corners are right angles, and that there may be a raised "A" on the top of the plug body. |- ! Mini‑AB{{efn|name=depc}}{{efn|name=ABrec}}<br />50px|A Mini‑AB receptacle: an opening 7 by 3 millimeters with a gray insulator in the center with the same shape as those of the Mini‑A and ‑B receptacles. The opening of the AB receptacle's opening is the union of those of the A and B receptacles, with only a slight narrowing in the lower half, to allow insertion of either plug type. | colspan="2" |Mini‑A{{efn|name=depc}}<br />50px|A Mini‑A plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑B plug only in that the sides of the wider upper part are flat, where in the Type‑B plug the widest part is only two rounded edges, and that there may be a raised "A" on the top of the plug body. | colspan="2" |Mini‑B<br />50px|A Mini‑B plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑A plug only in that the sides of the wider upper part are rounded, where in the Type‑A plug wide part continues downward a bit more providing flat sides, and there may be a raised "B" on the top of the plug body. |}
'''''Remarks:''''' {{notelist|refs= {{efn|name=USB42|USB4 2.0: Up to 80 Gbit/s each direction, or 120 in either direction and 40 the other}} {{efn|name=USB3|USB 3.''x'': 20, 10, or 5 Gbit/s, and USB 2.0: 480, 12, or 1.2 Mbit/s}} {{efn|name=USB2|USB 2.0: 480, 12, or 1.2 Mbit/s}} {{efn|name=Speed31|USB 3.''x'' (one lane only): 10, or 5 Gbit/s, and USB 2.0: 480, 12, or 1.2 Mbit/s}} {{efn|name=OtherP|Also standard for ''Thunderbolt 3'' and later. Also supports ''DisplayPort Alternate Mode''.}} {{efn|name=Lim2|Compatible, limited to the capabilities of USB 2.0}} {{efn|name=NoMicroA|There is no Micro‑A–specific receptacle.}} {{efn|name=ABrec|A device with a Type‑AB receptacle accepts both Type‑A and Type‑B plugs and the plugged devices function either as the host or as a peripheral device, accordingly: When the Type‑A plug of a cable is connected, the device with the Type‑AB receptacle functions as the host; when the Type‑B plug end is connected, it functions as a peripheral device.}} {{efn|name=depc|Deprecated}} }}
{| class="wikitable" summary="Table showing all allowed USB cables. The only modern USB cable has a Type‑C plug at each end; all others are designated ''legacy''. A legacy cable has an ''A'' end, which connects to (or toward) the host (or hub), and a ''B'' end, which connects to (or toward) a peripheral device (or hub). Plug options for the ''A'' end are shown in columns, and for the ''B'' end in rows. The cell at each intersection describes the validity and capabilities of a cable with the corresponding plugs." |+ USB cables and capabilities, by connector type<br /><small>Illustrations to scale</small> |- ! colspan="2" rowspan="2" {{diagonal split header|Plug at<br />''B'' end<br />(peripheral){{efn|name=A–A exception}}{{efn|name=defective devices}}|Plug at<br />''A'' end<br />(host)<br />{{efn|name=A–A exception}}{{efn|name=defective devices|Some devices, e.g. some smartphones, are defectively designed in that they ''can'' function as USB hosts, not just as peripheral devices, except that they have, incorrectly, Micro‑B or Mini‑B receptacles instead of ‑AB receptacles. Nonstandard cables to connect peripheral devices to these defective devices exist: Such a cable has a proper Type‑B plug at one end and at the other a plug electrically marked Type‑A that is mechanically Type‑B, allowing insertion and causing such a defective device to take the ''host'' role. When connected to a valid device that ''correctly'' has a Type‑B receptacle damage is unlikely since all Type‑B ports are unpowered by default, but no communication occurs.<ref>{{cite web |url=https://www.usb.org/sites/default/files/documents/usb_otg_and_eh_3-0_release_1_1_10may2012.pdf |title=On-The-Go and Embedded Host Supplement to the USB Revision 3.0 Specification |version=Revision 1.1 |date=May 10, 2012 |website=USB.org}}</ref>}} }} ! colspan="1" | Current ! colspan="4" | Legacy ! colspan="1" | Deprecated |- ! rowspan="1" style="vertical-align:bottom" | Type-C<br />center|57px|A Full-Featured Type‑C plug: a smooth metal shell, 8 by 2.5 millimeters, with rounded sides and rounded edges at the facing end. The end has a narrow slot with all contacts inside. The Full-Featured plug has 6 shield-contact springs, all more prominent than the four in the other Type‑C plugs, and all contacts are present except the center pair on one side. Type‑C plugs only vary in which contacts are present inside; they cannot be distinguished by touch and are difficult to discern visually without magnification. ! colspan="1" style="vertical-align:bottom" | USB 3.0<br />Standard‑A<br />78px|A USB 3.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the earlier version only in that it has five additional contacts deep inside and that the insulator is often bright blue. ! colspan="1" style="vertical-align:bottom" | USB 3.0<br />Micro‑A<br />76px|A USB 3.0 Micro‑A plug: a wide, flat metal shell, twelve by 2 millimeters, in two sections with latch springs protruding from the bottom side. It is distinct from the USB 3.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side of the wider section are chamfered, and that there may be a raised "A" on the top of the plug body. ! colspan="1" style="vertical-align:bottom" | USB 2.0<br />Standard‑A<br />78px|A USB 2.0 Standard‑A plug: a metal shell, 12 by 4 millimeters, with a plastic insulator body occupying the lower half of the space inside the shell. It is distinct from the later version only in that it lacks five additional contacts deep inside and that the insulator is generally not bright blue. ! colspan="1" style="vertical-align:bottom" | USB 2.0<br />Micro‑A<br />50px|A USB 2.0 Micro‑A plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side are chamfered, and that there may be a raised "A" on the top of the plug body. ! colspan="1" style="vertical-align:bottom" | Mini‑A<ref name="Deprecation of Mini-A and Mini-AB" /><br />50px|A Mini‑A plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑B plug only in that the sides of the wider upper part are flat, where in the Type‑B plug the widest part is only two rounded edges, and that there may be a raised "A" on the top of the plug body. |- ! colspan="1" rowspan="1" | Current ! colspan="1" rowspan="1" | Type‑C<br/>center|57px|A Full-Featured Type‑C plug: a smooth metal shell, 8 by 2.5 millimeters, with rounded sides and rounded edges at the facing end. The end has a narrow slot with all contacts inside. The Full-Featured plug has 6 shield-contact springs more prominent than in other Type‑C plugs, and all contacts are present except the center pair on one side. Type‑C plugs only vary in which contacts are present inside so cannot be distinguished by touch. | colspan="1" rowspan="1" {{yes|}}Up to {{nowrap|80 Gbit/s}},<br />or {{nowrap|120 Gbit/s}} either direction and 40 the other<br />(USB4 Gen 4)<ref name="Type-C Spec 2.4" /> | colspan="1" rowspan="1" style="border-bottom: none;" {{yes2|}}Up to {{nowrap|10 Gbit/s}}<br />{{nowrap|(USB 3.2 Gen 2×1)}}<ref name="Type-C Spec 2.4" /> | colspan="1" rowspan="1" {{No|Prohibited}}<ref name="Type-C Spec 2.4" />{{efn|name=AB problem}}{{efn|name=Prohibited}} | colspan="1" rowspan="1" {{operational|}}Up to {{nowrap|480 Mbit/s}} {{nowrap|half duplex}} {{nowrap|(USB 2.0)}}<ref name="Type-C Spec 2.4" /> | colspan="1" rowspan="1" {{No|Prohibited}}<ref name="Type-C Spec 2.4" />{{efn|name=AB problem}}{{efn|name=Prohibited}} | colspan="1" rowspan="1" {{No|Prohibited}}<ref name="Deprecation of Mini-A and Mini-AB" /><ref name="Type-C Spec 2.4" />{{efn|name=AB problem}}{{efn|name=Prohibited}} |- ! rowspan="6" | Legacy ! rowspan="1" style="vertical-align: bottom;"| USB 3.0<br />Standard‑B<br />57px|A USB 3.0 Standard‑B plug: 8 by 10 millimeters, with an 8-millimeter-wide lower section and a step inward to the 6-millimeter-wide upper section. There is a vertical bump on each side of the wider section, and on the face a wide rectangular opening in the center of the insulator and a smaller open space at the top, bordered by the shell. | colspan="1" rowspan ="2" style="border-top: none;"{{yes2|}}Up to {{nowrap|10 Gbit/s}}<br />{{nowrap|(USB 3.2 Gen 2×1)}}<ref name="Type-C Spec 2.4" /> | rowspan="2" colspan="2" style="border-top: none;"{{yes2|}}Up to {{nowrap|10 Gbit/s}}<br />{{nowrap|(USB 3.2 Gen 2×1)}}<ref name="3.1 Legacy Cable and Connector Spec 1.0" /> | rowspan="2" colspan="3" {{n/a}} |- ! rowspan="1" style="vertical-align: bottom;"| USB 3.0<br />Micro‑B<br />76px|A USB 3.0 Micro‑B plug: a wide, flat metal shell, twelve by 2 millimeters, in two sections with latch springs protruding from the bottom side. It is distinct from the USB 3.0 Micro‑A plug only in that the edges of the wider section are chamfered on the upper side and that there may a raised "B" on the top of the plug body. |- ! rowspan="1" style="vertical-align: bottom;"| USB 2.0<br />Standard‑B<br />57px|A USB 2.0 Standard‑B plug: 8 by 7 millimeters wide, with chamfered upper corners. There is a vertical bump on each side of the shell, and on the face a wide rectangular opening in the center of the insulator. | rowspan="3" {{operational|}}Up to {{nowrap|480 Mbit/s}} {{nowrap|half duplex}} {{nowrap|(USB 2.0)}}<ref name="Type-C Spec 2.4" /> | rowspan="3" colspan="2" {{n/a}} | rowspan="1" {{operational|}}Up to {{nowrap|480 Mbit/s}} {{nowrap|half duplex}} {{nowrap|(USB 2.0)}}<ref name="USB Spec 2.0"> {{cite web |author = <!-- not stated --> |date = April 27, 2000 |title = Universal Serial Bus Specification |version = 2.0 |url = https://usb.org/document-library/usb-20-specification |website = USB Implementers Forum |url-status = live |archive-url = https://web.archive.org/web/20231006051556/https://usb.org/document-library/usb-20-specification |archive-date = October 6, 2023 |access-date = March 23, 2025 }}</ref> | {{No|Prohibited}}{{efn|name=Micro-A plug to Standard-A receptacle}}<ref name="Micro-USB 1.01" />{{efn|name=Prohibited}} | rowspan="3" {{No|Prohibited}}<ref name="Deprecation of Mini-A and Mini-AB" />{{efn|name=Prohibited}} |- ! rowspan="1" style="vertical-align: bottom;"| USB 2.0<br />Micro‑B<br />50px|A USB 2.0 Micro‑B plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑A plug only in that the edges of the upper side are chamfered, where in the Type‑A plug all corners are right angles, and that there may be a raised "A" on the top of the plug body. | rowspan="2" {{operational|}}Up to {{nowrap|480 Mbit/s}} {{nowrap|half duplex}} {{nowrap|(USB 2.0)}}<ref name="Micro-USB 1.01" /> | {{operational|}}Up to {{nowrap|480 Mbit/s}} {{nowrap|half duplex}} {{nowrap|(USB 2.0)}}<ref name="Micro-USB 1.01" /> |- ! rowspan="1" colspan="1" style="vertical-align: bottom;" | Mini‑B<br />50px|A Mini‑B plug: a metal shell 7 by 3 millimeters, narrowing to 6 millimeters in the lower part, with no sharp protrusions. It is distinct from the Mini‑A plug only in that the sides of the wider upper part are rounded, where in the Type‑A plug wide part continues downward a bit more providing flat sides, and there may be a raised "B" on the top of the plug body. | {{No|Prohibited}}{{efn|name=Micro-A plug to Standard-A receptacle}}<ref name="Micro-USB 1.01" />{{efn|name=Prohibited}} |}
{{notelist|refs= {{efn|name=A–A exception| Every legacy USB cable has an ''A'' end and a ''B'' end, with the exception of a single special Type‑A–Type‑A cable type for operating system debugging and other host-to-host connection applications: This cable has a USB 3.0 Standard‑A plug at each end but with no connections for power (V<sub>BUS</sub>) or for the legacy data channel of USB 2 and USB 1 (D−, D+).<ref name="3.1 Legacy Cable and Connector Spec 1.0" /><ref name="3.1 Legacy Compliance 1.1"> {{cite web |author = <!-- not stated --> |date = April 3, 2018 |title = Universal Serial Bus 3.1 Legacy Connectors and Cable Assemblies Compliance Document |version = 1.1 |url = https://usb.org/sites/default/files/CabConn_Legacy_3_1_Compliance_Rev_1_1.pdf |website = USB Implementers Forum |url-status = live |archive-url = https://web.archive.org/web/20241127002415/https://www.usb.org/sites/default/files/CabConn_Legacy_3_1_Compliance_Rev_1_1.pdf |archive-date = November 27, 2024 |access-date = February 27, 2025 }}</ref> This exception, while safe, has no common application. Also there are valid A-to-A ''assemblies'', referred to loosely as ''cables'' (such as the Easy Transfer Cable), which are actually not simply cables but active peripheral devices: In USB terms, such a product is two peripherals, each one seen by one of the hosts to which the "cable" is connected.}} {{efn|name= Micro-A plug to Standard-A receptacle | There is no standard cable to directly connect a peripheral device with a Standard‑B or Mini‑B port directly to an On-The-Go host. Instead, a cable with a Standard‑A plug is used, and the Standard‑A plug is connected to a (specifically allowed) adapter that connects to the Micro‑AB receptacle of the On-The-Go host.}} {{efn|name=AB problem|A cable with a Type‑C plug and a plug that fits an Type‑AB receptacle (i.e. Micro or Mini) can be confusing in that the directionality of the cable may be unclear and its directionality determines whether an attached device takes the ''host'' or ''peripheral device'' role. To avoid this problem, the Type‑C connector is always the ''A'' end of such cables with the other end a Micro‑B or a Mini‑B. Type‑C–Micro‑A and Type‑C–Mini‑A cables are prohibited.}} {{efn|name=Prohibited| The USB standards do not allow cables with every combination of one Type‑A and one Type‑B plug, and nonstandard cables cannot be certified or marked with USB logos. However, cables with non-standard combinations of plugs exist. Provided that the one end is Type‑A and the other Type‑B (that one plug is an Type‑A type or Type‑C and the other a Type‑B type or Type‑C) a cable may function.}} }}
In addition to the above cable assemblies comprising two ''plugs'', receptacles are allowed in three ''adapter assemblies'': * Two ''legacy adapter assemblies'' for compatibility with equipment that predates USB‑C: ** USB 3.1 Standard‑A receptacle to Type‑C plug, to connect a legacy Standard‑A plug to a modern Type‑C receptacle<ref name="C Compliance 2.1b"> {{cite web |author = <!-- not stated --> |date = June 2021 |title = Universal Serial Bus Type‑C Connectors and Cable Assemblies Compliance Document |version = 2.1b |url = https://usb.org/sites/default/files/USB%20Type-C%20Connectors%20and%20Cable%20Assemblies%20Compliance%20Document%20Rev%202.1b.zip |website = USB Implementers Forum |access-date = February 27, 2025 }}</ref> ** USB 2.0 Micro‑B receptacle to Type‑C plug, to connect a legacy Micro‑B plug to a modern Type‑C receptacle<ref name="C Compliance 2.1b" /> * One older adapter, itself designated ''legacy'', predating USB‑C: Standard‑A receptacle to Micro‑A plug, giving a compact On-The-Go device, such as a camera or smartphone, a Standard‑A port for connecting peripherals, such as printers and mass storage devices. That is, to connect a Standard‑A plug to a Micro‑AB receptacle.<ref name="Micro-USB 1.01"> {{cite web |author = <!-- not stated --> |date = April 4, 2007 |title = Universal Serial Bus Micro-USB Cables and Connectors Specification |version = 1.01 |url = https://usb.org/document-library/usb-20-specification |website = USB Implementers Forum |url-status = live |archive-url = https://web.archive.org/web/20231006051556/https://usb.org/document-library/usb-20-specification |archive-date = October 6, 2023 |access-date = February 27, 2025 }}</ref><ref name="microspec" /> (All USB connectors except Type‑C were designated ''legacy'' in 2014.<ref name="C Compliance 2.1b" />)
{| class="wikitable" summary="Table describes all of three valid USB adapters. The first two are ''legacy adapters'' allowing legacy plugs to connect to the modern Type‑C receptacle. First, an adapter with a USB 3.0 Standard‑A receptacle and a Type‑C plug, allowing any Standard‑A plug to connect to a Type‑C receptacle. Second, an adapter with a USB 2.0 Micro‑B receptacle and a Type‑C plug. Last is a legacy-to-legacy adapter, with a USB 2.0 Standard‑A receptacle and a USB 2.0 Micro‑A plug." |+ USB adapters, by connector type |- ! colspan="1" rowspan="2" {{diagonal split header| Legacy<br />receptacle|Plug}} ! colspan="1" | Current ! colspan="1" | Legacy |- ! colspan="1" rowspan="1" style="vertical-align:bottom" | Type‑C<br />center|57px|A Full-Featured Type‑C plug: a smooth metal shell, 8 by 2.5 millimeters, with rounded sides and rounded edges at the facing end. The end has a narrow slot with all contacts inside. The Full-Featured plug has six shield-contact springs, all more prominent than the four in the other Type‑C plugs, and all contacts are present except the center pair on one side. Type‑C plugs only vary in which contacts are present inside; they cannot be distinguished by touch and are difficult to discern visually without magnification. ! colspan="1" rowspan="1" ! style="vertical-align:bottom" | USB 2.0 Micro‑A<br />50px |A USB 2.0 Micro‑A plug: a wide, flat metal shell, 7 by 2 millimeters, with latch springs protruding from the bottom side. It is distinct from the USB 2.0 Micro‑B plug only in that all outside corners are right angles, where in the Type‑B plug the corners on the upper side are chamfered, and that there may be a raised "A" on the top of the plug body. |- ! rowspan="1" rowspan="1" style="vertical-align:bottom;" | USB 3.0 Standard‑A<br />78px |A USB 3.0 Standard‑A receptacle: a rectangular opening five by twelve millimeters with a plastic protrusion inside near the top, the protrusion having notches for the five electrical contacts added for USB 3.x, or a single notch for the same. | colspan="1" rowspan ="1" style="border-top: none;"{{yes2|}}Up to {{nowrap|10 Gbit/s}} {{nowrap|(USB 3.2 Gen 2×1)}}<ref name="Type-C Spec 2.4" /><br /><small>to connect a legacy peripheral device to a Type‑C host</small> | colspan="1" rowspan="2" {{n/a}} |- ! rowspan="1" rowspan="1" style="vertical-align:bottom;" | USB 2.0 Micro‑B<br />50px|A USB 2.0 Micro‑B receptacle: an opening 7 by 2 millimeters, distinct from the USB 2.0 Micro‑AB receptacle only in that the upper corners narrow to preclude insertion of an Type‑A plug | rowspan="1" rowspan="1" {{operational|}}Up to {{nowrap|480 Mbit/s}} {{nowrap|half duplex}} {{nowrap|(USB 2.0)}}<ref name="Type-C Spec 2.4" /><br /><small>to connect a legacy charger or host to a Type‑C peripheral device</small> |- ! rowspan="1" rowspan="1" style="vertical-align:bottom;" | USB 2.0 Standard‑A<br />78px |A USB 2.0 Standard‑A receptacle: a rectangular opening five by twelve millimeters with a wide plastic protrusion inside above the center. It is distinct from the USB 3.x variant in that the protrusion lacks the notch or notches on its underside for five additional contacts. | colspan="1" rowspan="1" {{n/a}} | rowspan="1" rowspan="1" {{operational|}}Up to {{nowrap|480 Mbit/s}} {{nowrap|half duplex}} {{nowrap|(USB 2.0)}}<ref name="Micro-USB 1.01" /><br /><small>to connect a peripheral device to an On-The-Go device</small> |}
===Internal connectors=== USB 9-pin and 19-pin headers|thumb A computer's motherboard includes pin headers for connecting the motherboard to the USB ports on the computer case. The following types are standardized:<ref>{{cite web |title=Understanding Motherboard USB Headers and Ports {{!}} Newnex |url=https://newnex.com/motherboard-usb-header.php |website=newnex.com}}</ref> * 9-pin header for two USB 1.1/2.0 Type-A ports. There is also a 5-pin variant for a single port. Motherboards made before 2000 may have other layouts.<ref>{{cite web |title=FRONTX - Mother-board USB Pin Assignment - USB Header (pinout) Connection Guide |url=https://www.frontx.com/cpx108_2.html |website=www.frontx.com}}</ref> * 19-pin header for two USB 3.0 (also known as 3.1/3.2 Gen 1) Type-A ports. This is not backwards compatible with the 9-pin header;<ref>{{Cite web|url=https://www.intel.sg/content/dam/doc/technical-specification/usb3-internal-connector-cable-specification.pdf|title=USB 3.0 INTERNAL CONNECTOR AND CABLE SPECIFICATION}}</ref> there is no standard for running a newer signal (e.g. Gen 2) over this header, but there is enough signal integrity to do so in practice. * "Type-E" ports, which are not pin headers with an array of pins, but a port to plug into: ** 20-pin Key-A for a single full-featured Type-C, providing up to 80 Gbps in the case of USB4 2.0. (As the original definition is for USB 3.1 Gen 2 [aka USB 3.2 Gen 2, ×2 for two lanes in USB-C], the electrical connection between the case-port and the header may not be of high enough quality for 80 Gbps. USB4 40 Gbps should be achievable as it requires the same cable quality as USB 3.1 Gen 2.)<ref name=20p>{{cite web |title=USB 3.1 FRONT-PANEL INTERNAL CONNECTOR AND CABLE, REVISION 1.1|date=2017 |url=https://www.usb.org/sites/default/files/USB3p1_Front_Panel_CabCon_Implment_Doc_Rev1p1.pdf}}</ref><ref>{{Cite web|url=https://www.usb.org/sites/default/files/D2T2-2%20-%20USB4%20Cable%20and%20System.pdf|title=USB4 Cable Electricals and System Design}}</ref> It can also be used to provide one Type-A port up to USB 3.1/3.2 Gen 2. There is officially no provision for providing two Type-A ports from this header as it only provides one pair of legacy (USB 1.1/2.0) data pins.<ref name=20p/> The 20-pin headers are not backwards compatible with either 9 or 19-pin. ** 20-pin Key-B for two Type-A ports up to USB 3.1/3.2 Gen 2. This header differs from Key-A by reassigning the CC and SBU pins to legacy 1.1/2.0 data (D+, D−) and power (VBUS, GND). Physical keying prevents mixing of Key-A and Key-B port (headers) and plugs.<ref name=20p/> ** 40-pin, which is functionally the same as two 20-pin Key-A headers put side-by-side. Supports either two Type-C ports, one Type-C plus one Type-A port, or two Type-A ports. A 40-pin port can accept a 20-pin Key-A plug.<ref name=20p/>
All these systems are electrically compatible with each other like the USB external connectors are, so passive adapters can be used to mitigate physical incompatibilities, e.g. by converting 19-pin headers to 9-pin headers. It is even possible to convert a 19-pin header to a 20-pin header for USB-C use, albeit without CC and SBU functionality.
The shape and contact positions, i.e. footprints, for USB receptables soldered onto circuit boards (surface-mount devices) is partly standardized.
In addition, there is an ''embedded USB'' (eUSB2) specification describing using USB 2.0 for the communication between two chips on the same circuit board. It uses a lower signaling voltage compared to regular USB 2.0.<ref>{{cite web |title=SSZT427 Technical article {{!}} TI.com |url=https://www.ti.com/document-viewer/lit/html/SSZT427 |website=www.ti.com}}</ref>
===Proprietary connectors and formats=== Manufacturers of personal electronic devices might not include a USB standard connector on their product for technical or marketing reasons.<ref>{{cite web |url=http://anythingbutipod.com/2008/04/proprietary-cable-vs-standard-usb/ |title=Proprietary Cables vs Standard USB |date=April 30, 2008 |access-date=October 29, 2013 |website=anythingbutipod.com |archive-url=https://web.archive.org/web/20131113215722/http://anythingbutipod.com/2008/04/proprietary-cable-vs-standard-usb/ |archive-date=November 13, 2013}}</ref> For example, Olympus has been using a special cable called CB-USB8, one end of which has a special contact. Some manufacturers provide proprietary cables, such as Apple with the Lightning cable, that permit their devices to physically connect to a USB standard port. Full functionality of proprietary ports and cables with USB standard ports is not assured; for example, some devices only use the USB connection for battery charging and do not implement any data transfer functions.<ref>{{cite web |url=http://www.macworld.com/article/2028888/review-logitechs-ultrathin-mini-keyboard-cover-makes-the-wrong-tradeoffs.html |title=Review: Logitech's Ultrathin mini keyboard cover makes the wrong tradeoffs |date=February 25, 2013 |access-date=October 29, 2013 |author-first=Lex |author-last=Friedman |website=macworld.com |url-status=live |archive-url=https://web.archive.org/web/20131103072153/http://www.macworld.com/article/2028888/review-logitechs-ultrathin-mini-keyboard-cover-makes-the-wrong-tradeoffs.html |archive-date=November 3, 2013}}</ref>
== Cabling <span class="anchor" id="CABLING"></span>== [[File:USB Twisted Pair.svg|thumb|upright=1.2|A USB twisted pair, in which the ''Data+'' and ''Data−'' conductors are twisted together in a double helix. The wires are enclosed in a further layer of shielding.]]
The D± signals used by low, full, and high speed are carried over a twisted pair (typically unshielded) to reduce noise and crosstalk. SuperSpeed uses separate transmit and receive differential pairs, which additionally require shielding (typically, shielded twisted pair but twinax is also mentioned by the specification). Thus, to support SuperSpeed data transmission, cables contain twice as many wires and are larger in diameter.<ref>{{cite web |url=http://hantat.com/News-Read-459-1.html |title=What Is the USB 3.0 Cable Difference |publisher=Hantat |date=May 18, 2009 |archive-url=https://web.archive.org/web/20111211232404/http://hantat.com/News-Read-459-1.html |archive-date=December 11, 2011 |access-date=December 12, 2011}}</ref>
The USB 1.1 standard specifies that a standard cable can have a maximum length of {{convert|5|m|ftin}} with devices operating at full speed (12 Mbit/s), and a maximum length of {{convert|3|m|ftin}} with devices operating at low speed (1.5 Mbit/s).<ref>{{cite web |url=http://www.cablesplususa.com/pdf/USB_Cable_Length_Limitations.pdf |title=USB Cable Length Limitations |website=cablesplususa.com |date=November 3, 2010 |archive-url=https://web.archive.org/web/20141011015850/http://www.cablesplususa.com/pdf/USB_Cable_Length_Limitations.pdf |archive-date=October 11, 2014 |access-date=February 2, 2014}}</ref><ref>{{cite web |url=https://www.techwalla.com/articles/what-is-the-maximum-length-of-a-usb-cable |title=What is the Maximum Length of a USB Cable? |website=Techwalla.com |url-status=live |archive-url=https://web.archive.org/web/20171201043247/https://www.techwalla.com/articles/what-is-the-maximum-length-of-a-usb-cable |archive-date=December 1, 2017 |access-date=November 18, 2017}}</ref><ref name="faq">{{cite web |url=http://www.usb.org/developers/usbfaq#cab1 |title=USB Frequently Asked Questions: Cables and Long-Haul Solutions |website=USB.org |archive-url=https://web.archive.org/web/20140115191641/http://www.usb.org/developers/usbfaq/#cab1 |archive-date=January 15, 2014 |access-date=May 22, 2023}}</ref>
USB 2.0 provides for a maximum cable length of {{convert|5|m|ftin}} for devices running at high speed (480 Mbit/s). The primary reason for this limit is the maximum allowed round-trip delay of about 1.5 μs. If USB host commands are unanswered by the USB device within the allowed time, the host considers the command lost. When adding USB device response time, delays from the maximum number of hubs added to the delays from connecting cables, the maximum acceptable delay per cable amounts to 26 ns.<ref name="faq" /> The USB 2.0 specification requires that cable delay be less than {{nowrap|5.2 ns/m}} ({{nowrap|1.6 ns/ft}}, {{nowrap|{{gaps|192|000}} km/s}}), which is close to the maximum achievable transmission speed for standard copper wire.
The USB 3.0 standard does not directly specify a maximum cable length, requiring only that all cables meet an electrical specification: for copper cabling with AWG 26 wires the maximum practical length is {{convert|3|m|ftin}}.<ref>{{cite web |title=USB 3.0 Developers FAQ |url=http://janaxelson.com/usb3faq.htm#ca_maximum |author-last=Axelson |author-first=Jan |url-status=live |archive-url=https://web.archive.org/web/20161220073858/http://www.janaxelson.com/usb3faq.htm#ca_maximum |archive-date=December 20, 2016 |access-date=October 20, 2016}}</ref> For USB 3.x cables, the D± signals are usually shielded.
== Power <span class="anchor" id="POWER"></span>== {{See also|USB hub#Power}}
Downstream USB connectors supply power at a nominal {{nowrap|5 V DC}} via the V_BUS pin to upstream USB devices.
=== Voltage tolerance and limits === thumb|upright=1.2|Worst-case voltage drop topology of a USB 2.0 host to low-power device chain, at steady state
The tolerance on V_BUS at an upstream (or host) connector was originally ±5% (i.e. could lie anywhere in the range 4.75 V to 5.25 V). With the release of the USB Type-C specification in 2014 and its 3 A power capability, the USB-IF elected to increase the upper voltage limit to 5.5 V to combat voltage drop at higher currents.<ref>{{Cite web |date=March 1, 2021 |title=USB Type-C Revision 1.0 |url=https://www.those.ch/designtechnik/wp-content/uploads/2014/08/USB-Type-C-Specification-Release-1.0.pdf |url-status=live |archive-url=https://web.archive.org/web/20211103140823/https://www.those.ch/designtechnik/wp-content/uploads/2014/08/USB-Type-C-Specification-Release-1.0.pdf |archive-date=November 3, 2021 |access-date=November 3, 2021 |website=USB 3.0 Promoter Group}}</ref> The USB 2.0 specification (and therefore implicitly also the USB 3.''x'' specifications) was also updated to reflect this change at that time.<ref>{{cite web |date=November 3, 2021 |title=USB ECN USB 2.0 VBUS Max Limit |url=https://usb.org/document-library/usb-20-specification |url-status=live |archive-url=https://web.archive.org/web/20211103142016/https://www.usb.org/sites/default/files/usb_20_20211008.zip |archive-date=November 3, 2021 |access-date=November 3, 2021 |website=USB-IF}}</ref> A number of extensions to the USB Specifications have progressively further increased the maximum allowable V_BUS voltage: starting with 6.0 V with USB BC 1.2,<ref>{{cite web |date=March 15, 2015 |title=Battery Charging v1.2 Spec and Adopters Agreement |url=https://www.usb.org/sites/default/files/BCv1.2_070312_0.zip |url-status=live |archive-url=https://web.archive.org/web/20211103145550/https://www.usb.org/sites/default/files/BCv1.2_070312_0.zip |archive-date=November 3, 2021 |archive-format=PDF (Zipped) |access-date=November 3, 2021 |website=USB.org |at=Table 5-1 Voltages |format=PDF (Zipped)}}</ref> to 21.5 V with USB PD 2.0<ref name=":0">{{cite web |date=October 26, 2021 |title=USB Power Delivery Specifications 2.0 and 3. |url=https://www.usb.org/sites/default/files/USB%20Power%20Delivery%2020211026.zip |url-status=live |archive-url=https://web.archive.org/web/20211103143611/https://www.usb.org/sites/default/files/USB%20Power%20Delivery%2020211026.zip |archive-date=November 3, 2021 |archive-format=PDF (Zipped) |access-date=November 3, 2021 |website=USB.org |format=PDF (Zipped)}}</ref> and 50.9 V with USB PD 3.1,<ref name=":0" /> while still maintaining backwards compatibility with USB 2.0 by requiring various forms of handshake before increasing the nominal voltage above 5 V.
USB PD continues the use of the bilateral 5% tolerance, with allowable voltages of {{Abbr|PDO|Power Data Object
Data Object used to expose a Source Port's power capabilities or a Sink's power requirements as part of a Source_Capabilities or Sink_Capabilities Message respectively.
Fixed, Variable and Battery Power Data Objects are defined.}} ±5% (e.g. for a PDO of 9.0 V, the minimum and maximum limits are 8.55 V and 9.45 V, respectively). Overshoot (or undershoot) not exceeding ±0.5 V is allowed for up to 275 msec when changing to a higher (or lower) voltage.<ref name=":0" />
There are several minimum allowable voltages defined at different locations within a chain of connectors, hubs, and cables between an upstream host (providing the power) and a downstream device (consuming the power). To allow for voltage drops, the voltage at the host port, hub port, and device are specified to be at least 4.75 V, 4.4 V, and 4.35 V respectively by USB 2.0 for low-power devices,{{Efn|Low-power devices are those which draw less than 1 unit load. 1 unit load is 100 mA for USB 2.0 |name="low-power USB 2" |group="Power"}} but must be at least 4.75 V at all locations for high-power{{Efn|High-power devices in USB 2.0 are those that draw more than one unit load (up to a maximum of 5 unit loads). 1 unit load is 100 mA. |name="High-power USB 2" |group="Power"}} devices (however, high-power devices are required to operate as a low-powered device so that they may be detected and enumerated if connected to a low-power upstream port). The USB 3.''x'' specifications require that all devices must operate down to 4.00 V at the device port.
Unlike USB 2.0 and USB 3.2, USB4 does not define its own VBUS-based power model. Power for USB4 operation is established and managed as defined in the USB Type-C Specification and the USB PD Specification. {{Notelist|group="Power"}}
thumb|upright=1.2|Worst-case voltage drop topology of a USB 3.''x'' host to device chain, at steady state. Under transient conditions the supply at the device can momentarily drop from 4.0 V to 3.67 V.
=== Allowable current draw === {| class="wikitable floatright" |+ USB power standards |- ! Specification ! Current (max.) ! Voltage ! Power (max.) |- | Low-power device | 100 mA || 5 V || 0.50 W |- | Low-power SuperSpeed (USB 3.0) device | 150 mA || 5 V || 0.75 W |- | High-power device | 500 mA{{Efn|Up to 5 unit loads; with non-SuperSpeed devices, one unit load is 100 mA.}} || 5 V || 2.5 W |- | High-power SuperSpeed (USB 3.0) device | 900 mA{{Efn|Up to 6 unit loads; with SuperSpeed devices, one unit load is 150 mA.}} || 5 V || 4.5 W |- | Battery Charging (BC) 1.2 | 1.5 A || 5 V || 7.5 W |- | Single-lane SuperSpeed+ (USB 3.2 Gen 2×1) device | 1.5 A{{Efn|name=Vml|Up to 6 unit loads; with multi-lane devices, one unit load is 250 mA.}} || 5 V || 7.5 W |- | Power Delivery 3.0 SPR | 3 A || 5 V || 15 W |- | Power Delivery 3.0 SPR | 3 A || 9 V || 27 W |- | Power Delivery 3.0 SPR | 3 A || 15 V || 45 W |- | Power Delivery 3.0 SPR | 3 A || 20 V || 60 W |- | Power Delivery 3.0 SPR Type-C | 5 A{{efn|name="req_5A_cable"|>3 A (>60 W) operation requires an electronically marked cable rated at 5 A.}} || 20 V || 100 W |- | Power Delivery 3.1 EPR Type-C | 5 A{{efn|name="req_5A_cable"}} || 28 V{{efn|name="req_EPR_cable"|>20 V (>100 W) operation requires an electronically marked Extended Power Range (EPR) cable.}} || 140 W |- | Power Delivery 3.1 EPR Type-C | 5 A{{efn|name="req_5A_cable"}} || 36 V{{efn|name="req_EPR_cable"|>20 V (>100 W) operation requires an electronically marked Extended Power Range (EPR) cable.}} || 180 W |- | Power Delivery 3.1 EPR Type-C | 5 A{{efn|name="req_5A_cable"}} || 48 V{{efn|name="req_EPR_cable"|>20 V (>100 W) operation requires an electronically marked Extended Power Range (EPR) cable.}} || 240 W |- | colspan=4 | {{Notelist}} |}
The limit to device power draw is stated in terms of a ''unit load'' which is 100 mA for USB 2.0, or 150 mA for SuperSpeed (i.e. USB 3.''x'') devices. Low-power devices may draw at most 1 unit load, and all devices must act as low-power devices before they are configured. A high-powered device must be configured, after which it may draw up to 5 unit loads (500 mA), or 6 unit loads (900 mA) for SuperSpeed devices, as specified in its configuration because the maximum power may not always be available from the upstream port.<ref name="usb.org">{{cite web |url=http://www.usb.org/developers/docs/ |title=USB.org |website=USB.org |access-date=June 22, 2010 |url-status=live |archive-url=https://web.archive.org/web/20120619021820/http://www.usb.org/developers/docs |archive-date=June 19, 2012}}</ref><ref>{{cite web |url=http://esd.cs.ucr.edu/webres/usb11.pdf |title=Universal Serial Bus 1.1 Specification |date=September 23, 1998 |access-date=November 24, 2014 |website=cs.ucr.edu |pages=150, 158 |url-status=live |archive-url=https://web.archive.org/web/20150102233110/http://esd.cs.ucr.edu/webres/usb11.pdf |archive-date=January 2, 2015}}</ref><ref>{{cite web |url=http://www.usb.org/developers/docs/usb_20_070113.zip |title=Universal Serial Bus 2.0 Specification, Section 7.2.1.3 Low-power Bus-powered Functions |date=April 27, 2000 |access-date=January 11, 2014 |website=usb.org |format=ZIP |url-status=live |archive-url=https://web.archive.org/web/20130910140635/http://www.usb.org/developers/docs/usb_20_070113.zip |archive-date=September 10, 2013}}</ref><ref>{{cite web |url=http://www.usb.org/developers/docs/usb_20_070113.zip |title=Universal Serial Bus 2.0 Specification, Section 7.2.1.4 High-power Bus-powered Functions |date=April 27, 2000 |access-date=January 11, 2014 |website=usb.org |format=ZIP |url-status=live |archive-url=https://web.archive.org/web/20130910140635/http://www.usb.org/developers/docs/usb_20_070113.zip |archive-date=September 10, 2013}}</ref>
A bus-powered hub is a high-power device providing low-power ports. It draws one unit load for itself and one unit load for each of at most four ports. The hub may also have some non-removable devices in place of ports, a common example being a keyboard with two low-power A ports included, sufficient for pointing devices such as mice. (Such a keyboard is, in USB terms, one hub and one peripheral device.) A self-powered hub is a device that provides high-power ports by supplementing the power supply from the host with its own external supply. Optionally, the hub controller may draw power for its operation as a low-power device, but all high-power ports must draw from the hub's self-power.
Where devices (for example, high-speed disk drives) require more power than a high-power device can draw,<ref>{{cite web |url=http://www.xbitlabs.com/articles/storage/display/25inch-500-640-750gb-hdd-roundup_17.html#sect0 |title=Roundup: 2.5-inch Hard Disk Drives with 500 GB, 640 GB and 750 GB Storage Capacities (page 17) |website=xbitlabs.com |date=June 16, 2010 |access-date=July 9, 2010 |archive-url=https://web.archive.org/web/20100628183615/http://www.xbitlabs.com/articles/storage/display/25inch-500-640-750gb-hdd-roundup_17.html#sect0 |archive-date=June 28, 2010}}</ref> they function erratically, if at all, from bus power of a single port. USB provides for these devices as being self-powered. However, such devices may come with a Y-shaped cable that has two USB plugs (one for power and data, the other for only power), so as to draw power as two devices.<ref>{{cite web |url=http://www.hitachigst.com/hdd/support/SignatureMiniFAQ.html#a2 |title=I have the drive plugged in but I cannot find the drive in "My Computer", why? |website=hitachigst.com |date=May 16, 2001 |access-date=March 30, 2012 |archive-url=https://web.archive.org/web/20110215144332/http://www.hitachigst.com/hdd/support/SignatureMiniFAQ.html#a2 |archive-date=February 15, 2011}}</ref> Such a cable is non-standard, with the specification stating that "use of a 'Y' cable (a cable with two A-plugs) is prohibited on any USB peripheral", meaning that "if a USB peripheral requires more power than allowed by the USB specification to which it is designed, then it must be self-powered."<ref>{{cite web |url=http://compliance.usb.org/index.asp?UpdateFile=Policies#72 |title=USB-IF Compliance Updates |website=Compliance.usb.org |date=September 1, 2011 |access-date=January 22, 2014 |url-status=live |archive-url=https://web.archive.org/web/20140203192507/http://compliance.usb.org/index.asp?UpdateFile=Policies#72 |archive-date=February 3, 2014}}</ref>
Since USB 2.0, USB standardized overcurrent protection mechanisms for USB hosts and USB devices.<ref>{{Cite web| title=USB 2.0 and USB 3.0 Circuit Protection Considerations for Hard Disc Drives | url=https://media.digikey.com/pdf/Application%20Notes/AMP%20Application%20Notes/USB_2.0_3.0_CP_Considerations.pdf | archive-url=https://web.archive.org/web/20130416052601/http://media.digikey.com/pdf/Application%20Notes/AMP%20Application%20Notes/USB_2.0_3.0_CP_Considerations.pdf | archive-date=2013-04-16}}</ref>
{{Reflist|group="Power"}}
=== USB battery charging <span class="anchor" id="ACA"></span><span class="anchor" id="BCS"></span><span class="anchor" id="62680-3"></span>=== <!-- "USB Battery Charging" and "USB Battery Charging Specification 1.0" redirect here. --> '''USB Battery Charging''' ('''BC''') defines a ''charging port'', which may be a ''charging downstream port'' (CDP), with data, or a ''dedicated charging port'' (DCP), without data. Dedicated charging ports can be found on USB power adapters to run and charge attached devices and charge battery packs. Charging ports on a host with both kinds will be labeled.<ref name="USBBC1.2">{{cite web | url = https://usb.org/sites/default/files/BCv1.2_070312_0.zip | title = Battery Charging Specification, Revision 1.2 | date = March 15, 2012 | access-date = August 13, 2021 | publisher = USB Implementers Forum | url-status = live | archive-url = https://web.archive.org/web/20210310200454/https://usb.org/sites/default/files/BCv1.2_070312_0.zip | archive-date = March 10, 2021 }}</ref>
The charging device identifies a charging port by non-data signaling on the D+ and D− terminals. A dedicated charging port places a resistance not exceeding 200 Ω across the D+ and D− terminals.{{r|USBBC1.2|p=§1.4.7; table 5-3}}<!-- Section 1.4.7: "Dedicated Charging Port", page 3. Table 5-3: "Resistances", page 46. Details omitted for brevity. -->
Per the base specification, any device attached to a ''standard downstream port'' (SDP) must initially be a low-power device, with high-power mode contingent on later USB configuration by the host. Charging ports, however, can immediately supply between 0.5 and 1.5 A of current. The charging port must not apply current limiting below 0.5 A, and must not shut down below 1.5 A or before the voltage drops to 2 V.<ref name="USBBC1.2" />
Since these currents are larger than in the original standard, the extra voltage drop in the cable reduces noise margins, causing problems with High Speed signaling. Battery Charging Specification 1.1 specifies that charging devices must dynamically limit bus power current draw during High Speed signaling;<ref name="USBBC1.1">{{cite web | url = http://www.usb.org/developers/devclass_docs/batt_charging_1_1.zip | archive-url = https://web.archive.org/web/20140329080504/http://www.usb.org/developers/devclass_docs/batt_charging_1_1.zip | title = Battery Charging Specification, Revision 1.1 | date = April 15, 2009 | access-date=September 23, 2009 | archive-date = March 29, 2014 | publisher = USB Implementers Forum }}</ref> 1.2 specifies that charging devices and ports must be designed to tolerate the higher ground voltage difference in High Speed signaling.
Revision 1.2 of the specification was released in 2010. It made several changes and increased limits, including allowing 1.5 A on charging downstream ports for unconfigured devices—allowing High Speed communication while having a current up to 1.5 A. Also, support was removed for charging-port detection via resistive mechanisms.<ref name="battchargespec1.2">{{cite web |url=http://www.usb.org/developers/docs/devclass_docs/BCv1.2_070312.zip |title=Battery Charging v1.2 Spec and Adopters Agreement |date=March 15, 2012 |access-date=May 13, 2021 |publisher=USB Implementers Forum |format=Zip |url-status=live |archive-url=https://web.archive.org/web/20141006113700/http://www.usb.org/developers/docs/devclass_docs/BCv1.2_070312.zip |archive-date=October 6, 2014 }}</ref>
{{anchor|Brick ID}}Before the Battery Charging Specification was defined, there was no standardized way for the portable device to inquire how much current was available. For example, Apple's iPod and iPhone chargers indicate the available current by voltages on the D− and D+ lines (sometimes also called "Apple Brick ID"). When D+ = D− = 2.0 V, the device may pull up to 900 mA. When D+ = 2.0 V and D− = 2.8 V, the device may pull up to 1 A of current.<ref name=icharge>{{cite web | url = http://www.ladyada.net/make/mintyboost/icharge.html | title = Minty Boost — The mysteries of Apple device charging | website = Lady Ada | date = May 17, 2011 | archive-url = https://web.archive.org/web/20120328161525/http://www.ladyada.net/make/mintyboost/icharge.html | archive-date = March 28, 2012 }}</ref> When D+ = 2.8 V and D− = 2.0 V, the device may pull up to 2 A of current.<ref>{{cite web |date= October 5, 2011 |url= http://www.instructables.com/id/Modify-a-cheap-USB-charger-to-feed-an-iPod-iPhone/ |title= Modify a cheap USB charger to feed an iPod, iPhone |url-status= live |archive-url= https://web.archive.org/web/20111007195308/http://www.instructables.com/id/Modify-a-cheap-USB-charger-to-feed-an-iPod-iPhone/ |archive-date= October 7, 2011 }}</ref> The maximum power delivered with this method was 12.48 W (5.2 V, 2.4 A),<ref>{{Cite web |title=About Apple USB power adaptors – Apple Support (AU) |url=https://support.apple.com/en-au/120548 |access-date=March 21, 2025 |website=Apple Support |language=en}}</ref> with D+ = D− = 2.7 V.<ref>{{cite web |title=On an Apple 12W USB Charger, how are the D+ and D- lines configured? |url=https://electronics.stackexchange.com/a/223239 |website=Electrical Engineering Stack Exchange |language=en}}</ref>
==== Accessory Charger Adapter ==== A USB On-The-Go (OTG) device has a single Micro-AB port (or, formerly, a Mini-AB port) for charging as well as for connecting either to a host or to peripheral devices. An Accessory Charger Adapter (ACA) allows simultaneous connection to a charger and either to a host or to peripheral devices, with the charger providing power to both the OTG device and any connected peripheral devices. For example, a keyboard can connect to a smartphone, or a printer, a keyboard, and a flash drive can connect to a smartphone through a USB hub, with the ACA capable of charging the smartphone and powering the keyboard, flash drive, and hub; or the smartphone can connect to a computer (host) that does not provide full power for charging, while the ACA provides full charging power.
An Accessory Charger Adapter has three ports: ''OTG'', ''Charger'', and ''Accessory''. The OTG port connects to the On-The-Go device through a permanently-attached (''captive'') cable with a (mechanically) Micro-A plug. The Charger port is visibly marked ''Charger Only'' and does not support USB communication with the OTG device. It is either a Micro-B receptacle or a captive cable; such a captive cable either has a Standard-A plug or is permanently attached to a charger. The Accessory port is either a Micro-AB or Standard-A receptacle. An ''A'' receptacle by definition can only connect to peripheral devices; the Micro-AB receptacle can be used to connect either a host or peripheral devices. The captive plug of the OTG port is unusual in that, unlike a normal Micro-A plug, which is not only mechanically identifiable as an ''A'' plug but also electrically marked as such (causing an OTG device to behave as a host), the Micro-A plug of the Accessory Charger Adapter electrically becomes ''B'' when a Micro-B plug is connected to the (Micro-AB) Accessory port, causing the OTG device to behave as a peripheral.{{r|USBBC1.2|at=§6}}
===USB Power Delivery <span class="anchor" id="PD"></span><span class="anchor" id="PD-R1.0"></span><span class="anchor" id="PD-R2.0V1.0"></span>=== <!-- "USB Power Delivery" and "USB Power Delivery Specification" redirect here. --> [[File:USB Type-C Charging Logo.svg|thumb|upright=0.5|The USB Type-C Charging logo (USB4 20 Gbps port)]]
{| class="wikitable floatright" style=text-align:right |+ USB PD Rev. 1.0 source profiles<ref name=PD1.0/> |- ! Profile ! +5 V ! +12 V ! +20 V |- ! 0 | colspan=3 {{n/a|Reserved}} |- ! 1 | rowspan=5 valign="top" | 3.0 A, 15 W{{Efn|name="default-profile"|Default start-up profile}} | {{n/a}} | rowspan=3 {{n/a}} |- ! 2 | 1.5 A, 18 W |- ! 3 | rowspan=2 valign="top" | 3.0 A, 36 W |- ! 4 | 3.0 A, 60 W |- ! 5 | 5.0 A, 60 W | 5.0 A, 100 W |- | colspan=4 | {{Notelist}} |}
{| class="wikitable floatright" style=text-align:right |+ USB Power Delivery rev. 2.0/3.''x'' power rules |- ! Power ! style=max-width:14em | Minimum USB‑C<br />cable required ! Voltage ! Current |- ! ≤ 15 W ! rowspan=4 | Any{{Efn-ua|name="60W"|''60 W'' label required on both plug bodies by <br/>current standard, not required on older cables}}<ref name="USBPD20" /><ref name="USBPD30" /><ref name=USBPD31/> | 5 V | rowspan=4 | ≤ 3.0 A |- ! ≤ 27 W | 9 V |- ! ≤ 45 W | 15 V |- ! ≤ 60 W | 20 V |- style="border-top: double; border-bottom: double;" ! ≤ 100 W ! 5 A, or 100 W{{Efn-ua|name="emarked-cable"|Electronically marked}} | 20 V | halign="right" | ≤ 5.0 A |- ! ≤ 140 W{{Efn-ua|name="EPR"|USB PD Extended Power Range}} ! rowspan=3 | 240 W{{Efn-ua|name="emarked-cable"}}{{Efn-ua|name="240W"|''240 W'' label required on both plug bodies}}<ref name=USBPD31/> | 28 V | rowspan=3 | ≤ 5.0 A |- ! ≤ 180 W{{Efn-ua|name="EPR"}} | 36 V |- ! ≤ 240 W{{Efn-ua|name="EPR"}} | 48 V |- | colspan=9 | {{Notelist-ua}} |}
thumb|Power rule of USB Power Delivery Revision 3.1
In July 2012, the USB Promoters Group announced the finalization of the '''USB Power Delivery''' ('''USB-PD''') specification (USB PD rev. 1), an extension that specifies using certified ''PD aware'' USB cables with standard USB Type-A and Type-B connectors to deliver increased power (more than the 7.5 W maximum allowed by the previous USB Battery Charging specification) to devices with greater power demands. (USB-PD A and B plugs have a mechanical mark while Micro plugs have a resistor or capacitor attached to the ID pin indicating the cable capability.) USB-PD Devices can request higher currents and supply voltages from compliant hosts—up to 2 A at 5 V (for a power consumption of up to 10 W), and optionally up to 3 A or 5 A at either 12 V (36 W or 60 W) or 20 V (60 W or 100 W).<ref>{{cite web|url=http://www.techspot.com/news/52321-usb-30-superspeed-update-to-eliminate-need-for-chargers.html|title=USB 3.0 SuperSpeed Update to Eliminate Need for Chargers |last=Burgess|first=Rick|date=April 22, 2013 |publisher=TechSpot}}</ref> In all cases, both host-to-device and device-to-host configurations are supported.<ref>{{cite web |url=http://www.usb.org/press/USB_Power_Delivery_Spec_Completion_FINAL_072712.pdf |title=USB 3.0 Promoter Group Announces Availability of USB Power Delivery Specification |date=July 18, 2012 |access-date=January 16, 2013 |url-status=live |archive-url=https://web.archive.org/web/20130120031237/http://www.usb.org/press/USB_Power_Delivery_Spec_Completion_FINAL_072712.pdf |archive-date=January 20, 2013 }}</ref>
The intent is to permit uniformly charging laptops, tablets, USB-powered disks and similarly higher-power consumer electronics, as a natural extension of existing European and Chinese mobile telephone charging standards. This may also affect the way electric power used for small devices is transmitted and used in both residential and public buildings.<ref name="usb-power-delivery">{{cite news |url= https://www.economist.com/news/international/21588104-humble-usb-cable-part-electrical-revolution-it-will-make-power-supplies?fsrc=scn/fb/wl/pe/edisonsrevenge |title= Edison's revenge |newspaper= The Economist |date= October 19, 2013 |access-date= October 23, 2013 |url-status= live |archive-url= https://web.archive.org/web/20131022091918/http://www.economist.com/news/international/21588104-humble-usb-cable-part-electrical-revolution-it-will-make-power-supplies?fsrc=scn%2Ffb%2Fwl%2Fpe%2Fedisonsrevenge |archive-date= October 22, 2013 }}</ref><ref name=PD1.0>{{cite web |url=http://www.usb.org/developers/powerdelivery/PD_1.0_Introduction.pdf |title=USB Power Delivery — Introduction |date=July 16, 2012 |access-date=January 6, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130123140132/http://www.usb.org/developers/powerdelivery/PD_1.0_Introduction.pdf |archive-date=January 23, 2013 }}</ref> The standard is designed to coexist with the previous USB Battery Charging specification.<ref>{{Cite web|url=https://www.usb.org/usb-charger-pd|title=USB Charger (USB Power Delivery) {{pipe}} USB-IF|website=www.usb.org}}</ref>
The first Power Delivery specification (Rev. 1.0) defined six fixed power profiles for the power sources. PD-aware devices implement a flexible power management scheme by interfacing with the power source through a bidirectional data channel and requesting a certain level of electrical power, variable up to 5 A and 20 V depending on supported profile. The power configuration protocol can use BMC coding over the configuration channel (CC) wire if one is present, or a 24 MHz BFSK-coded transmission channel on the V<sub>BUS</sub> line.<ref name="PD1.0" />
The USB Power Delivery specification revision 2.0 (USB PD Rev. 2.0) has been released as part of the USB 3.1 suite.<ref name="USBPD20">{{citation | title=Universal Serial Bus Power Delivery Specification revision 2.0, version 1.2 | chapter=10 Power Rules | date=March 25, 2016 | chapter-url=http://www.usb.org/developers/docs/ | publisher=USB Implementers Forum | access-date=April 9, 2016 | url-status=live | archive-url=https://archive.today/20240526002457/https://www.webcitation.org/685PPTw8f?url=http://www.usb.org/developers/docs/ | archive-date=May 26, 2024 }}</ref><ref>{{cite web|url=https://www.usb.org/documents|title=USB 3.1 Specification |archive-url=https://web.archive.org/web/20120619021820/http://www.usb.org/developers/docs|archive-date=June 19, 2012|url-status=live|access-date=November 11, 2014}}</ref><ref>{{cite web |url=https://www.anandtech.com/show/8539/usb-power-delivery-v20-and-billboard-device-class-v10-specifications-finalized |archive-url=https://web.archive.org/web/20140918031940/http://www.anandtech.com/show/8539/usb-power-delivery-v20-and-billboard-device-class-v10-specifications-finalized |url-status=dead |archive-date=September 18, 2014 |title=USB Power Delivery v2.0 Specification Finalized - USB Gains Alternate Modes |website=AnandTech.com }}</ref> It covers the USB-C cable and connector with a separate configuration channel, which now hosts a DC coupled low-frequency BMC-coded data channel that reduces the possibilities for RF interference.<ref>{{cite web|title=USB Future Specifications Industry Reviews|url=http://www.usb.org/developers/USB-Futures.pdf|access-date=August 10, 2014|url-status=live|archive-url=https://web.archive.org/web/20140729083949/http://www.usb.org/developers/USB-Futures.pdf|archive-date=July 29, 2014}}</ref> Power Delivery protocols have been updated to facilitate USB-C features such as cable ID function, Alternate Mode negotiation, increased V<sub>BUS</sub> currents, and V<sub>CONN</sub>-powered accessories.
As of specification revision 2.0, version 1.2, the six fixed power profiles for power sources have been deprecated.<ref>{{cite tech report |title=Universal Serial Bus Power Delivery Specification revision 2.0, version 1.2 |chapter=A. Power Profiles |date=March 25, 2016 |chapter-url=http://www.usb.org/developers/docs/usb_31_040816.zip |publisher=USB Implementers Forum |access-date=April 9, 2016 |archive-url=https://web.archive.org/web/20160412211620/http://www.usb.org/developers/docs/usb_31_040816.zip |archive-date=April 12, 2016 }}</ref> USB PD Power Rules replace power profiles, defining four normative voltage levels at 5, 9, 15, and 20 V. Instead of six fixed profiles, power supplies may support any maximum source output power from 0.5 W to 100 W.
{{Anchor|Programmable Power Supply|PPS}} The USB Power Delivery specification revision 3.0 defines an optional Programmable Power Supply (PPS) protocol that allows granular control over V<sub>BUS</sub> output, allowing a voltage range of 3.3 to 21 V in 20 mV steps, and a current specified in 50 mA steps, to facilitate constant-voltage and constant-current charging. Revision 3.0 also adds extended configuration messages and fast role swap and deprecates the BFSK protocol.<ref name="USBPD30">{{citation|title=Universal Serial Bus Power Delivery Specification revision 3.0, version 1.1|chapter-url=https://www.usb.org/documents|archive-url=https://archive.today/20240526002457/https://www.webcitation.org/685PPTw8f?url=http://www.usb.org/developers/docs/|url-status=live|chapter=10 Power Rules|publisher=USB Implementers Forum|access-date=September 5, 2017|archive-date=May 26, 2024}}</ref>{{rp|at=Table 6.26}}<ref name="PD_HK2016">{{Cite web|url=http://www.usb.org/developers/presentations/USB_DevDays_Hong_Kong_2016_-_USB_PD.pdf|title=USB Power Delivery|date=October 20, 2016|website=usb.org|publisher=USB-IF |archive-url=https://web.archive.org/web/20161220102831/http://www.usb.org/developers/presentations/USB_DevDays_Hong_Kong_2016_-_USB_PD.pdf|archive-date=December 20, 2016}}</ref><ref>{{cite web |url=https://e2e.ti.com/blogs_/b/powerhouse/archive/2016/07/14/usb-power-delivery-2-vs-3 |title=USB Power Delivery 2.0 vs 3.0 |first=Deric |last=Waters |date=July 14, 2016 |website=E2E.TI.com |access-date=July 30, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170730234342/https://e2e.ti.com/blogs_/b/powerhouse/archive/2016/07/14/usb-power-delivery-2-vs-3 |archive-date=July 30, 2017 }}</ref> PPS can reduce heat generation of both charger and device.
thumb|upright=0.5|The Certified USB Fast Charger logo, indicating support for the Programmable Power Supply (PPS) protocol in USB Power Delivery (PD) chargers
On January 8, 2018, USB-IF announced the Certified USB Fast Charger logo for chargers that use the Programmable Power Supply (PPS) protocol from the USB Power Delivery 3.0 specification.<ref>{{cite press release|url=https://www.businesswire.com/news/home/20180108005383/en/USB-IF-Introduces-Fast-Charging-Expand-Certified-USB|title=USB-IF Introduces Fast Charging to Expand its Certified USB Charger Initiative|date=January 9, 2018|access-date=January 10, 2018}}</ref>
{{Anchor|Extended Power Range|EPR}} In May 2021, the USB PD promoter group launched revision 3.1 of the specification.<ref name="USBPD31">{{citation|title=Universal Serial Bus Power Delivery Specification revision 3.1, version 1.0|chapter-url=https://usb.org/document-library/usb-power-delivery|chapter=10 Power Rules|publisher=USB Implementers Forum|access-date=September 5, 2017}}</ref> Revision 3.1 adds Extended Power Range (EPR) mode which allows higher voltages of 28, 36, and 48 V, providing up to 240 W of power (48 V at 5 A), and the "Adjustable Voltage Supply" (AVS) protocol which allows specifying the voltage from a range of 15 to 48 V in 100 mV steps.<ref>[https://www.eenewseurope.com/news/usb-pd-boosts-usb-c-power-delivery-240w-48v USB-PD boosts USB-C power delivery to 240W at 48V]. Nick Flaherty, EENews. May 28, 2021</ref><ref>[https://web.archive.org/web/20210528122248/https://www.anandtech.com/show/16712/usbc-power-delivery-hits-240w-with-extended-power-range USB-C Power Delivery Hits 240W with Extended Power Range]. Ganesh T S, Anandtech. May 28, 2021</ref> Higher voltages require electronically marked EPR cables that support 5 A operation and incorporate mechanical improvements required by the USB Type-C standard revision 2.1; existing power modes are retroactively renamed Standard Power Range (SPR). In October 2021 Apple introduced a 140 W (28 V 5 A) GaN USB PD charger with new MacBooks,<ref>{{Cite web|date=October 30, 2021|title=Teardown of Brand New Apple 140W USB-C GaN Charger|url=https://www.chargerlab.com/teardown-of-brand-new-apple-140w-usb-c-gan-charger/|access-date=November 15, 2021}}</ref> and in June 2023 Framework introduced a 180 W (36 V 5 A) GaN USB PD charger with the Framework 16.<ref name="framework">{{Cite web |title=Framework Laptop 16 Deep Dive - 180W Power Adapter |url=https://frame.work/blog/framework-laptop-16-deep-dive---180w-power-adapter |access-date=February 28, 2024 |website=Framework }}</ref> The AVS protocol is not backward compatible with the PPS protocol. A charger that supports AVS may not support PPS as well.
In October 2023, the USB PD promoter group launched revision 3.2 of the specification. The AVS protocol now works with the old standard power range (SPR), down to a minimum of 9 V.<ref name="USBPD32">{{citation |title=Universal Serial Bus Power Delivery Specification revision 3.2, version 1.0 |url=https://www.usb.org/sites/default/files/USB%20PD%20R3.2%20V1.0_1.zip |publisher=USB Implementers Forum |access-date=February 13, 2023 }}</ref>{{rp|at=§10.2.2}}
Prior to Power Delivery, mobile phone vendors used custom protocols to exceed the 7.5 W cap on the USB Battery Charging Specification (BCS). For example, Qualcomm's Quick Charge 2.0 is able to deliver 18 W at a higher voltage, and VOOC delivers 20 W at the normal 5 V.<ref>{{Cite web |url=https://www.cnet.com/news/fast-charging-phones-quick-charge-dash-charging/ |title=How fast can a fast-charging phone charge if a fast-charging phone can charge really fast? |website=CNet |access-date=December 4, 2016 }}</ref> Some of these technologies, such as Quick Charge 4, eventually became compatible with USB PD again.<ref>{{Cite web |url=http://www.anandtech.com/show/10846/qualcomm-announces-quick-charge-4 |archive-url=https://web.archive.org/web/20161117204242/http://www.anandtech.com/show/10846/qualcomm-announces-quick-charge-4 |url-status=dead |archive-date=November 17, 2016 |title=Qualcomm Announces Quick Charge 4: Supports USB Type-C Power Delivery |work=AnandTech |access-date= December 13, 2016}}</ref>
=== Charge controllers ===
{{Update|section|date=August 2024|reason=Be aware: Full of erroneous, incomplete and inconsiderate content, primarily focuses on mobile devices, and lacks of sources. }}
{{As of|2024}} mainstream USB PD charging controllers support up to 100 W through a single port, with a few up to 140 W<ref>{{cite web |title=Teardown of Anker 140W PD3.1 USB-C GaN Charger (717 Charger) |date=October 26, 2022 |url=https://www.chargerlab.com/teardown-of-anker-140w-pd3-1-usb-c-gan-charger-717-charger/}}</ref><ref>{{citation |title=140W PD 3.1 Power Adapters, the future of USB C Power Delivery | date=January 2, 2023 |url=https://www.youtube.com/watch?v=x4euVfT1ksk |access-date=March 8, 2024}}</ref> and custom built up to 180 W.{{r|framework}}{{Update inline|date=July 2025|reason=240w is theoretically now available, the relevant standards are more mature?}}
However the maximal power values are barely used in practice, especially for charging of mobile phones: The used standard or used USB-C chargers still remains at 1,5A@5V (=7.5W), which is the same as for USB-A. Only few chargers (sources) and charged devices (phones, clients) can really communicate, and fit the supply/demand combinations, so charging often remains just slow, at the USB-A standard. Some do comply together to use some negotiated PDO (power delivery objects), but their values are static. And because there can be at most only seven PPSs (preprogrammed power supply), only a few devices can really use the effectiveness of APDOs (Augmented Power Data Object, intervals of values, dynamic by increments of 20/50 mV/mA), usually only two these dynamic offered, leaving five options for some static ones. And even if overheating is prevented, e.g. with 4.1V@2.8A (11.48W), the charging is mostly not even close to the upper power limits of the devices, mostly 27W (9V@3A). That is because the voltages supported by phones are usually 5V or luckily also 9V (3.3-11V on APDO), and 3A at most, often 2.22A only, for voltages over 9V, so 20W is even lower upper limit for power delivery in practice, and still as a peak optimal value.
Another reason for differences in speed of charging, the power delivered to mobile phones, are different approachs of producers: E.g. Samsung prefers max charging speed, accepting power even out of USB-C/PPS specifications, so 5A @4.2V (21W) are measurable. On the other hand Sony Xperia shows the very opposite extreme, following strictly the PPS specifications, so when the charging status is out of the official, it quickly defaults down to the basic 1.5A (7W) charging, the "classical slow", effectively protecting the phone from overheating and prolonging lifetime of its battery.
Higher powers than 27W/33W are then accomplished by higher current (5A), and higher voltage (20V), which render the upper limit 100W (or 60W @3A). But such high power is not commonly possible for mobile phones, and for currents over 3A special protocols and cables (with electronics inside connectors) are usually needed, e.g. E-marker.
=== Sleep-and-charge ports === thumb|A yellow USB port denoting sleep-and-charge
Sleep-and-charge USB ports can be used to charge electronic devices even when the computer that hosts the ports is switched off. Normally, when a computer is powered off the USB ports are powered down. This feature has also been implemented on some laptop docking stations allowing device charging even when no laptop is present.<ref>{{cite web|title=ThinkPad Ultra Dock|url=http://shop.lenovo.com/us/en/itemdetails/40A20090US/460/76C432D671BE45E6A425ED543A9591C2|website=lenovo.com|access-date=September 16, 2016|url-status=live|archive-url=https://web.archive.org/web/20160917084037/http://shop.lenovo.com/us/en/itemdetails/40A20090US/460/76C432D671BE45E6A425ED543A9591C2|archive-date=September 17, 2016}}</ref> On laptops, charging devices from the USB port when it is not being powered from AC drains the laptop battery; most laptops have a facility to stop charging if their own battery charge level gets too low.<ref>{{cite web |url= http://www.mytoshiba.com.au/file/download/resource/file/12585/NB200-UserGuide.pdf |title= Toshiba NB200 User Manual |location= UK |date= March 1, 2009 |access-date= January 26, 2014 |url-status= live |archive-url= https://web.archive.org/web/20140219115326/http://www.mytoshiba.com.au/file/download/resource/file/12585/NB200-UserGuide.pdf |archive-date= February 19, 2014 }}</ref>
On Dell, HP and Toshiba laptops, sleep-and-charge USB ports are marked with the standard USB symbol with an added lightning bolt or battery icon on the right side.<ref>{{cite web | url = https://www.dell.com/support/article/nl-nl/sln155147/usb-powershare-feature-on-dell-laptops?lang=en | title = USB PowerShare Feature | date = September 15, 2019 | access-date = June 15, 2020 | website = dell.com }}</ref> Dell calls this feature ''PowerShare'',<ref>{{cite web | url = http://www.dell.com/support/troubleshooting/an/en/andhs1/KCS/KcsArticles/ArticleView?c=an&l=en&s=dhs&docid=608993 | title = USB PowerShare Feature | date = June 5, 2013 | access-date = December 4, 2013 | website = dell.com | url-status = live | archive-url = https://web.archive.org/web/20131108231014/http://www.dell.com/support/troubleshooting/an/en/andhs1/KCS/KcsArticles/ArticleView?c=an&l=en&s=dhs&docid=608993 | archive-date = November 8, 2013 }}</ref> and it needs to be enabled in the BIOS. Toshiba calls it ''USB Sleep-and-Charge''.<ref>{{cite web | url = http://www.toshiba.com/us/sleep-and-charge | title = USB Sleep-and-Charge Ports | access-date = December 21, 2014 | website = toshiba.com | url-status = live | archive-url = https://web.archive.org/web/20141214094949/http://www.toshiba.com/us/sleep-and-charge | archive-date = December 14, 2014 }}</ref> On Acer Inc. and Packard Bell laptops, sleep-and-charge USB ports are marked with a non-standard symbol (the letters ''USB'' over a drawing of a battery); the feature is called ''Power-off USB''.<ref>{{cite web | url = http://packard-bell-scandic.custhelp.com/app/answers/detail/a_id/29967/~/usb-charge-manager | title = USB Charge Manager | access-date = April 25, 2014 | website = packardbell.com | archive-date = 2018-11-20 | archive-url = https://web.archive.org/web/20181120082018/http://packard-bell-scandic.custhelp.com/app/answers/detail/a_id/29967/~/usb-charge-manager | url-status = dead }}</ref> Lenovo calls this feature ''Always On USB''.<ref>{{Cite web |url=https://support.lenovo.com/nl/en/solutions/ht503671 |title=How to configure the system to charge devices over USB port when it is off - idea/Lenovo laptops - NL |website=support.lenovo.com |access-date=April 7, 2020 }}</ref>
=== Mobile device charger standards === {{Main|Universal charger}}
==== In China ==== Starting in 2007, all new mobile phones applying for a license in China are required to use a USB port as a power port for battery charging.<ref>{{cite magazine |url=http://www.eetimes.com/rss/showArticle.jhtml?articleID=199800238&cid=RSSfeed_eetimes_newsRSS |title=China to enforce universal cell phone charger |magazine=EE Times |author=Cai Yan |date=May 31, 2007 |access-date=August 25, 2007 |url-status=live |archive-url=https://web.archive.org/web/20070929095523/http://www.eetimes.com/rss/showArticle.jhtml?articleID=199800238&cid=RSSfeed_eetimes_newsRSS |archive-date=September 29, 2007 }}</ref><ref>The Chinese technical standard: {{Cite web | url = http://www.dianyuan.com/bbs/u/63/2015571206841181.pdf | title = YD/T 1591-2006, Technical Requirements and Test Method of Charger and Interface for Mobile Telecommunication Terminal Equipment | language = zh |website=Dian yuan | archive-url = https://web.archive.org/web/20110515212645/http://www.dianyuan.com/bbs/u/63/2015571206841181.pdf | archive-date = May 15, 2011 }}</ref> This was the first standard to use the convention of shorting D+ and D− in the charger.<ref>{{cite web |first1=Crystal |last1=Lam |first2=Harry |last2=Liu |url=http://www.eetimes.com/document.asp?doc_id=1275077&print=yes |title=How to conform to China's new mobile phone interface standards |publisher=Wireless Net DesignLine |date=October 22, 2007 |access-date=June 22, 2010 |url-status=live |archive-url=https://web.archive.org/web/20140514165523/http://www.eetimes.com/document.asp?doc_id=1275077&print=yes |archive-date=May 14, 2014 }}</ref>
==== OMTP/GSMA Universal Charging Solution ==== In September 2007, the Open Mobile Terminal Platform group (a forum of mobile network operators and manufacturers such as Nokia, Samsung, Motorola, Sony Ericsson, and LG) announced that its members had agreed on Micro-USB as the future common connector for mobile devices.<ref>{{cite news |url=http://www.news.com/2100-1041_3-6209247.html |title=Pros Seem to Outdo Cons in New Phone Charger Standard |website=News.com |date=September 20, 2007 |access-date=November 26, 2007 }}</ref><ref>{{cite press release |url=http://www.omtp.org/News/Display.aspx?Id=4ec69ecb-0978-4df6-b045-34557aabbcbd |title=Broad Manufacturer Agreement Gives Universal Phone Cable Green Light |publisher=OTMP |date=September 17, 2007 |access-date=November 26, 2007 |archive-url=https://web.archive.org/web/20090629183154/http://www.omtp.org/News/Display.aspx?Id=4ec69ecb-0978-4df6-b045-34557aabbcbd |archive-date=June 29, 2009 }}</ref>
The GSM Association (GSMA) followed suit on February 17, 2009,<ref name="gsm20090217">{{Cite press release | url= http://www.gsmworld.com/newsroom/press-releases/2009/2548.htm | publisher= GSM World | title= Agreement on Mobile phone Standard Charger | archive-url= https://web.archive.org/web/20090217192039/http://www.gsmworld.com//newsroom//press-releases//2009//2548.htm | archive-date= February 17, 2009 }}</ref><ref>{{cite web|url=http://www.omtp.org/Publications/Display.aspx?Id=4dda105f-8472-4c12-ba04-75dd3c1d4ca6 |title=Common Charging and Local Data Connectivity |publisher=Open Mobile Terminal Platform |date=February 11, 2009 |access-date=February 11, 2009 |archive-url=https://web.archive.org/web/20090329233721/http://www.omtp.org/Publications/Display.aspx?Id=4dda105f-8472-4c12-ba04-75dd3c1d4ca6 |archive-date=March 29, 2009 }}</ref><ref>{{cite web |url=http://www.gsmworld.com/our-work/mobile_planet/universal_charging_solution.htm |title=Universal Charging Solution ~ GSM World |publisher=GSM world |access-date=June 22, 2010 |archive-url=https://web.archive.org/web/20100626073016/http://www.gsmworld.com/our-work/mobile_planet/universal_charging_solution.htm |archive-date=June 26, 2010 }}</ref><ref>{{cite web |url= http://www.planetanalog.com/article/printableArticle.jhtml?articleID=218501515 |archive-url= https://archive.today/20120909022205/http://www.planetanalog.com/article/printableArticle.jhtml?articleID=218501515 |archive-date= September 9, 2012 |title= Meeting the challenge of the universal charge standard in mobile phones |publisher=Planet Analog |access-date=June 22, 2010 }}</ref> and on April 22, 2009, this was further endorsed by the CTIA – The Wireless Association,<ref>{{cite press release | url = http://www.ctia.org/media/press/body.cfm/prid/1817 | title = The Wireless Association Announces One Universal Charger Solution to Celebrate Earth Day | publisher = CTIA | date = April 22, 2009 | access-date = June 22, 2010 | archive-url = https://web.archive.org/web/20101214154849/http://ctia.org/media/press/body.cfm/PRID/1817 | archive-date = December 14, 2010 }}</ref> with the International Telecommunication Union (ITU) announcing on October 22, 2009, that it had also embraced the Universal Charging Solution as its "energy-efficient one-charger-fits-all new mobile phone solution", and added: "Based on the Micro-USB interface, UCS chargers will also include a 4-star or higher efficiency rating—up to three times more energy-efficient than an unrated charger."<ref>{{cite press release |url=http://www.itu.int/newsroom/press_releases/2009/49.html |title=Universal Phone Charger Standard Approved |publisher=ITU |date=October 22, 2009 |access-date=May 22, 2023 |archive-url=https://web.archive.org/web/20100327101058/http://www.itu.int/newsroom/press_releases/2009/49.html |archive-date=March 27, 2010 }}</ref>
==== EU smartphone power supply standard ==== In June 2009, the European Commission organized a voluntary Memorandum of Understanding (MoU) to adopt micro-USB as a common standard for charging smartphones marketed in the European Union. The specification was called the common external power supply. The MoU lasted until 2014. The common EPS specification (EN 62684:2010) references the USB Battery Charging Specification and is similar to the GSMA/OMTP and Chinese charging solutions.<ref>{{cite web | url = http://ec.europa.eu/enterprise/rtte/chargers.htm | title = chargers | location = EU | publisher = EC | date = June 29, 2009 | access-date = June 22, 2010 | archive-url = https://web.archive.org/web/20091023232430/http://ec.europa.eu/enterprise/rtte/chargers.htm | archive-date = October 23, 2009 }}</ref><ref>{{cite magazine |url=https://www.wired.com/gadgetlab/2009/06/europe-gets-universal-cellphone-charger-in-2010/ |title=Europe gets universal cellphone charger in 2010 |magazine=Wired |date=June 13, 2009 |access-date=June 22, 2010 |url-status=live |archive-url=https://web.archive.org/web/20100818031835/http://www.wired.com/gadgetlab/2009/06/europe-gets-universal-cellphone-charger-in-2010/ |archive-date=August 18, 2010 }}</ref> In January 2011, the International Electrotechnical Commission (IEC) released its version of the (EU's) common EPS standard as IEC 62684:2011.<ref>{{cite web |url=http://www.iec.ch/newslog/2011/nr0311.htm |title=One size-fits-all mobile phone charger: IEC publishes first globally relevant standard |publisher=International Electrotechnical Commission |date=February 1, 2011 |access-date=February 20, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120103141101/http://www.iec.ch/newslog/2011/nr0311.htm |archive-date=January 3, 2012 }}</ref>
In 2022, the Radio Equipment Directive 2022/2380 made USB-C compulsory as a mobile phone charging standard from 2024, and for laptops from 2026.<ref>{{Cite web |date=April 20, 2022 |title=Common charger: MEPs agree on proposal to reduce electronic waste |url=https://www.europarl.europa.eu/news/en/press-room/20220412IPR27115/common-charger-meps-agree-on-proposal-to-reduce-electronic-waste |archive-url=https://web.archive.org/web/20220422162233/https://www.europarl.europa.eu/news/en/press-room/20220412IPR27115/common-charger-meps-agree-on-proposal-to-reduce-electronic-waste |archive-date=April 22, 2022 |access-date=April 20, 2022 |website=European Parliament}}</ref>
=== Faster-charging standards === A variety of (non-USB) standards support charging devices faster than the USB Battery Charging standard. When a device doesn't recognize the faster-charging standard, generally the device and the charger fall back to the USB battery-charging standard of 5 V at 1.5 A (7.5 W). When a device detects it is plugged into a charger with a compatible faster-charging standard, the device pulls more current or the device tells the charger to increase the voltage or both to increase power (the details vary between standards).<ref name="kumar">{{cite magazine |first1=Ajay |last1=Kumar |first2=Steven |last2=Winkelman |first3=Dave |last3=LeClair |url=https://www.pcmag.com/article/359908/what-is-fast-charging |title=What Is Fast Charging? |date=July 27, 2022<!--"Updated"; originally 2018 we believe--> |magazine=PCMag |access-date=May 21, 2023 }}</ref>
Such standards include:<ref name="kumar" /><ref>{{cite web |last1=Hill |first1=Simon |last2=Revilla |first2=Andre |last3=Chandler |first3=Simon |url=https://www.digitaltrends.com/mobile/how-does-fast-charging-work/ |title=How does fast charging work? Here's every single standard compared |website=Digital Trends |date=July 1, 2021 |access-date=August 20, 2022}}</ref>
* Apple "Brick ID" 2 A and 2.4 A charging (described above, does not use BC negotiation) * Google fast charging * Huawei SuperCharge * MediaTek Pump Express * Motorola TurboPower * Oppo Super VOOC Flash Charge, are also known as ''Dash Charge'' or ''Warp Charge'' on OnePlus devices and ''Dart Charge'' on Realme devices * Qualcomm Quick Charge (QC) * Samsung Adaptive Fast Charging
=== Non-standard devices === Some USB devices require more power than is permitted by the specifications for a single port. This is common for external hard and optical disc drives, and generally for devices with motors or lamps. Such devices can use an external power supply, which is allowed by the standard, or use a dual-input USB cable, one input of which is for power and data transfer, the other solely for power, which makes the device a non-standard USB device. Some USB ports and external hubs can, in practice, supply more power to USB devices than required by the specification but a standard-compliant device may not depend on this.
In addition to limiting the total average power used by the device, the USB specification limits the inrush current (i.e., the current used to charge decoupling and filter capacitors) when the device is first connected. Otherwise, connecting a device could cause problems with the host's internal power. USB devices are also required to automatically enter ultra low-power suspend mode when the USB host is suspended. Nevertheless, many USB host interfaces do not cut off the power supply to USB devices when they are suspended.<ref>{{cite web |title=Part 2 - Electrical |url=http://www.usbmadesimple.co.uk/ums_2.htm|publisher=MQP Electronics |access-date=December 29, 2014 |url-status=live |archive-url=https://web.archive.org/web/20141224203350/http://www.usbmadesimple.co.uk/ums_2.htm |archive-date=December 24, 2014 }}</ref>
Some non-standard devices use the USB 5 V power supply without participating in a proper USB network, which negotiates power draw with the host interface; these devices typically violate the standards by drawing more power than is allowed without negotiation. Examples include USB-powered keyboard lights, fans, mug coolers and heaters, battery chargers, miniature vacuum cleaners, and even miniature lava lamps. In most cases, these items contain no digital circuitry, and thus are not standard-compliant USB devices. This may cause problems with some computers, such as drawing too much current and damaging circuitry. Prior to the USB Battery Charging Specification, the USB specification required that devices connect in a low-power mode (100 mA maximum) and communicate their current requirements to the host, which then permits the device to switch into high-power mode.
Some devices predating USB Power Delivery, when plugged into charging ports, draw even more power (10 watts) than the Battery Charging Specification allows, using proprietary methods but without violating USB standards, maintaining full compatibility—the iPad is one such device;<ref>{{cite web |url=http://www.macobserver.com/tmo/article/watt_to_know_about_iphone_ipad_power_adapters/ |title=Watt to Know About iPhone & iPad Power Adapters {{pipe}} Analysis |date=September 30, 2011 |publisher=The Mac Observer |access-date=December 12, 2011 |url-status=live |archive-url=https://web.archive.org/web/20111210104210/http://www.macobserver.com/tmo/article/watt_to_know_about_iphone_ipad_power_adapters/ |archive-date=December 10, 2011 }}</ref> it negotiates the current pull with data pin voltages.<ref name="icharge" /> Barnes & Noble Nook Color devices also require a special charger that can provide 1.9 A.{{Citation needed|date=July 2025}}
=== PoweredUSB === {{Main|PoweredUSB}}
PoweredUSB is a proprietary extension, from long before USB Power Delivery, that adds four pins supplying up to 6 A at 5 V, 12 V, or 24 V. It is commonly used in point-of-sale systems to power peripherals such as barcode readers, credit card terminals, and printers.
==See also== * USB-to-serial adapter * USB communications
==References== {{Reflist}} {{DC power delivery standards}} {{USB}}
Category:USB