USB‑C, or USB Type‑C, is a 24-pin reversible connector (not a protocol) that supersedes all previous USB connectors, which were designated legacy in 2014. This connector also supersedes Mini DisplayPort and Lightning connectors. USB-C is widely used for multiple purposes: exchanging data with peripheral devices, such as external drives, mobile phones, keyboards, track-pads, and mice, or between hosts; transferring A/V-data to displays and speakers; or powering peripheral devices and getting powered by power adapters, either through directly wired connectors or indirectly via hubs and docking stations. This connector type can be used for other data transfer protocols besides USB, such as Thunderbolt, PCIe, DisplayPort, and HDMI. It is considered extensible, allowing the support of future protocols.
The design for the USB‑C connector was initially developed in 2012 by members of the USB Implementers Forum, with Intel, HP Inc., and Texas Instruments being distinguished on the design document, though Apple Inc. and Microsoft among others also contributed. The Type‑C Specification 1.0 was published by the USB Implementers Forum (USB-IF) on August 11, 2014. In 2016 it was adopted by the International Electrotechnical Commission as "IEC 62680-1-3".
The USB Type‑C connector has 24 pins and is reversible. The designation C distinguishes it from the various USB connectors it replaced, all termed either Type‑A or Type‑B. Whereas earlier USB cables had a host end A and a peripheral device end B, a USB‑C cable connects either way; and for interoperation with older equipment, there are cables with a Type‑C plug at one end and either a Type‑A (host) or a Type‑B (peripheral device) plug at the other.
The designation C refers only to the connector's physical configuration, or form factor, not to be confused with the connector's specific capabilities and performance, such as Thunderbolt 3, DisplayPort 2.0, USB 3.2 Gen 2×2. While USB‑C is the single modern connector for all USB protocols, there are valid uses of the connector that do not involve any USB protocol. Based on the protocols supported by all, host, intermediate devices (hubs), and peripheral devices, a USB‑C connection normally provides much higher data rates, and often more electrical power, than anything using the superseded connectors.
A device with a Type‑C connector does not necessarily implement any USB transfer protocol, USB Power Delivery, or any of the Alternate Modes: the Type‑C connector is common to several technologies while mandating only a few of them.
USB 3.2, released in September 2017, fully replaced the USB 3.1 (and therefore also USB 3.0) specifications. It preserves the former USB 3.1 SuperSpeed and SuperSpeedPlus architectures and protocols, though introduces two additional operational modes by newly applying a two-lane configuration with signalling rates of 5 Gbit/s (resulting speed of USB 10Gbps with two lanes; raw data rate: 1.212 GB/s) and 10 Gbit/s (USB 20Gbps speed; raw data rate: 2.422 GB/s). They are only applicable with Full-Featured USB‑C cables and connectors and hosts, hubs, and peripheral devices that use them.
USB4 specification, released in 2019, is the first USB protocol standard that is applicable exclusively via USB‑C.
Ease of use The USB‑C standard simplifies usage by specifying cables having identical plugs on both ends; orientation is moot. Also, the plugs are flat but can be inserted in either orientation.
Symmetry Mechanically, the USB‑C receptacles have two-fold rotational symmetry because a plug may be inserted into a receptacle in either of two orientations. The ends are also mechanically interchangeable, because both end have the same type of plug.
Electrically, USB‑C plugs are not symmetric, as can be seen in the tables of pin layouts. Also, the two ends of the USB‑C are electrically different, as can be seen in the table of cable wiring.
Logically, the plugs are completely symmetrical. The illusion of symmetry results from how devices respond to the cable. Software makes the plugs and cables behave as though they are symmetric. According to the specifications, "Determination of this host-to-device relationship is accomplished through a Configuration Channel (CC) that is connected through the cable."
Universal application The USB‑C standard attempts to eliminate the need to have different cables for other communication technologies, such as Thunderbolt, PCIe, HDMI, DisplayPort and more. Over the past decade since 2014, many companies including Samsung Electronics, Apple Inc. and Transsion have adopted the USB‑C standard into their products. USB‑C cables can contain circuit boards and processors giving them much more capability than simple circuit connections.
Overview USB‑C cables interconnect hosts and peripheral devices, replacing various other electrical cables and connectors, including all earlier (legacy) USB connectors, HDMI connectors, DisplayPort ports, and 3.5 mm audio jacks.
Name USB Type‑C and USB‑C are trademarks of the USB Implementers Forum.
Connectors
The 24-pin double-sided connector is slightly larger than the non-SuperSpeed, USB 2.0 Micro connectors, with a USB‑C receptacle opening measuring 8.34mm× 2.56mm, 6.20mm deep.
Cables
Type‑C cables can be split among various categories and subcategories. The first one is USB 2.0 vs Full-Featured. USB 2.0 Type‑C cables have very limited wires and are only good for USB 2.0 communications and power delivery. They are also called charging cables colloquially. Conversely, Full-Featured cables need to have all wires populated and in general support Alternate Modes and are further distinguished by their speed rating.
Full-Featured cables exist in different speed grades. Their technical names, the operation mode, use the "Gen A" notation, each higher number increasing capabilities in terms of bit rates. The marketing names are based on the theoretically highest bit rate a connection should fulfill – but in reality never can –, namely "USB 5Gbps", "USB 10Gbps", "USB 20Gbps", "USB 40Gbps", and so on. The Full-Featured cables, can support at least USB 3.x, USB Power Delivery and DisplayPort.
A Gen 1 (signalling rate of 5 Gbit/s) cable supports that rate on every one of its two lanes (2*2 twisted data wire pairs). So it can be used to establish a USB 3.2 Gen 1x2 operation mode with nominally 10 Gbit/s (2*5 Gbit/s) between two USB 3.2, or USB4 or newer capable hosts connected by a Fully-Featured USB-C cable.
According the specification USB4 and USB4 2.0, the implementation of the USB 3.2 Gen 2x2 operation mode, resulting in nominally 20 Gbit/s, is only optional; indeed most USB4 controllers do not implement it. In other words, the "USB 20Gbps" will only be achieved by a USB4 or more modern version of an operation mode, such as USB4 Gen 2x2, with USB4 capable devices and Fully-Featured USB-C cables (and intermediate hubs) of a rate of "USB 20Gbps" (I.e. all 4 twisted data wire pairs are wired) or higher between a host and a peripheral device.
The USB Implementers Forum certifies valid cables so they can be marked accordingly with the official logos and users can distinguish them from non-compliant products. There have been simplifications in the logos. Previous logos and names also referenced specific USB protocols like SuperSpeed for the USB 3 family of connections or USB4 directly. The current official names and logos have removed those references as most full-featured cables can be used for USB4 connections as well as USB 3 connections.
In order to achieve longer cable lengths, cable variants with active electronics to amplify the signals also exist. The Type‑C standard mostly mandates these active cables to behave similarly to passive cables with vast backwards compatibility, but they are not mandated to support all possible features and typically have no forward compatibility to future standards. Optical cables are even allowed to further reduce the backwards compatibility. For example, an active cable may not be able to use all high speed wire-pairs in the same direction (as used for DisplayPort connections), but only in the symmetric combinations expected by classic USB connections. Passive cables have no such limitations.
Power delivery
Every USB‑C cable must support at least 3 amps of current and up to 20 volts for up to 60 watts of power according to the USB PD specification. Cables were also allowed to support up to 5 A while retaining the 20 V limit, allowing up to 100 W of power; however, the 20 V limit for 5 A cables has been deprecated in favor of 48 V. The combination of higher voltage support and 5 A current support is called Extended Power Range (EPR) and allows for up to 240 W (48 V, 5 A) of power according to the USB PD specification.
E-Marker All Type‑C cables except the minimal combination of USB 2.0 and only 3 A must contain E-Marker chips that identify the cable and its capabilities via the USB CC protocol. This identification data includes information about product/vendor, cable connectors, USB signalling protocol (USB 2.0, USB 3.x, etc), passive/active construction, use of VCONN power, available VBUS voltages and currents, latency, RX/TX directionality, SOP controller mode, and hardware/firmware version. It also can include further vendor-defined messages (VDM) that detail support for Alt Modes or vendor-specific functionality outside of the USB standards.
Hosts and peripheral devices For any two pieces of equipment connecting over USB, one is a host (with a downstream-facing port, DFP) and the other is a peripheral device (with an upstream-facing port, UFP). Some products, such as mobile phones, can take either role, whichever is opposite that of the connected equipment. Such equipment is said to have Dual-Role-Data (DRD) capability, which was known as USB On-The-Go in the previous specification. With USB‑C, when two such devices are connected, the roles are first randomly assigned, but a swap can be commanded from either end, although there are optional path and role detection methods that would allow equipment to select a preference for a specific role. Furthermore, Dual-Role equipment that implements USB Power Delivery may swap data and power roles independently using the Data Role Swap or Power Role Swap processes. This allows for charge-through hub or docking station applications such as a portable computer acting as a host to connect to peripherals but being powered by the dock, or a computer being powered by a display, through a single USB‑C cable.
USB‑C devices may optionally provide or consume bus power currents of 1.5 A and 3.0 A (at 5 V) in addition to baseline bus power provision; power sources can either advertise increased USB current through the configuration channel or implement the full USB Power Delivery specification using both the BMC-coded configuration line and the legacy BFSK-coded VBUS line.
All older USB connectors (all Type‑A and Type‑B) are designated legacy. Connecting legacy and modern, USB‑C equipment requires either a legacy cable assembly (a cable with any Type‑A or Type‑B plug on one end and a Type‑C plug on the other) or, in very specific cases, a legacy adapter assembly.