USB4

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Superseded	USB 3.2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 40 Gbit/s 80 Gbit/s 120 Gbit/s asymmetric

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 bit 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 mandates backwards compatibility to USB 2.0, USB 3.x and DisplayPort connections^[6]. The dynamic sharing of bandwidth of a USB4 connection is achieved by carrying virtualized "tunnels" of other connections. This includes tunneling of USB3 and DP connections. Other protocols, such as PCI Express and Ethernet can also be tunneled, even without a way to access these directly directly from USB4 ports.

USB4 also incorporates some elements and shares principles with the Thunderbolt 3 protocol; however, interoperability with Thunderbolt 3 products is mandatory only for select USB4 device types.^[7]