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. 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 PD protocol. This identification data includes information about product/vendor, cable connectors, USB signalling protocol (2.0, Gen speed rating , Gen 2), passive/active construction, use of VCONN power, available VBUS current, 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. 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. An older device can connect to a modern (USB‑C) host by using a legacy cable, with a Standard-B, Mini-B, or Micro-B plug on the device end and a USB‑C plug on the other. Similarly, a modern device can connect to a legacy host by using a legacy cable with a USB‑C plug on the device end and a Standard-A plug on the host end. Legacy adapters with USB‑C receptacles are "not defined or allowed" by the specification because they can create "many invalid and potentially unsafe" cable combinations (being any cable assembly with two
A ends or two
B ends). However, exactly two types of USB adapters with Type‑C plugs are defined: An adapter with a Standard‑A receptacle (for connecting a legacy device to a modern host, and supporting up to 10 Gbit/s), and one with a Micro‑B receptacle (for connecting a modern device to a legacy host or power supply, and supporting up to USB 2.0). to allow for the new Liquid Corrosion Mitigation Mode, this mode allowed a device with a Type‑C port to drive analog headsets directly through an audio adapter with a 3.5 mm jack, providing three analog audio channels (left and right output and a monaural microphone input). Unlike superficially similar
Lightning adapters, which handle all analog conversion and audio amplification internally, the adapters that used this Accessory Mode contained no electronics and required that the host device have all the additional components to handle analog audio
digital-to-analog converters and amplifiers for audio output and an
analog-to-digital converter to handle the analog microphone signal. Such an adapter could optionally include a USB‑C charge-through port to allow 500 mA device charging. The engineering specification states that an analog headset shall not use a USB‑C plug instead of a 3.5 mm plug. In other words, a headset with a USB‑C plug must always support digital audio (but optionally could support the Accessory Mode). Analog signals used the USB 2.0 differential pair contacts (Dp and Dn for right and left) and the two side-band use contacts for microphone and ground. The presence of the audio accessory was signaled through the configuration channel and VCONN. With the deprecation of Analog Audio mode, the Type-C specification strongly recommends using USB Audio Device Class 4.0 while also recommending version 2.0. ==Specifications==