USB4

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USB4

Type	USB
Production history
Designer	USB Promoter Group
Designed	29 August 2019; 4 years ago (2019-08-29)
Superseded	USB 3.2
Daisy chain	No
Audio signal	DisplayPort
Video signal	DisplayPort
Connector	USB-C
Electrical
Max. voltage	48 V (PD 3.1)
Max. current	5 A (PD)
Data
Data signal	Yes
Bitrate	20 Gbit/s (optionally up to 120 Gbit/s)

USB4 (Universal Serial Bus 4), sometimes erroneously referred to as USB 4.0, is the most recent technical specification of the USB (Universal Serial Bus) data communication standard. The USB Implementers Forum originally announced USB4 in 2019.

USB4 enables multiple devices to dynamically share a single high-speed data link. USB4 devices must support a data communication signaling rate of at least 20 gigabits (Gbit/s). The current version allows bit rates of 40 Gbit/s (since USB4 version 1.0) and 80 Gbit/s (since USB4 version 2.0).^[1][2] USB4 is only defined for the USB-C connector and its Type-C specification^[3] regulates the connector, cables and also power delivery features across all uses of USB-C cables, in part^[4] with the USB Power Delivery specification.^[5]

The USB4 standard is backwards compatible to USB 2.0, USB 3.2 and DP functionality. The dynamic sharing of bandwidth of a USB4 connection is achieved by carrying virtualized "tunnels" of other connections, like the previously mentioned ones. In addition to these also natively available connections, USB4 also supports other protocols, such as PCI Express and Ethernet.

USB4 also incorporates the (for some kind of devices optional) Thunderbolt 3 protocol; however, interoperability with Thunderbolt 3 products is mandatory only for select USB4 device types.^[6]