USB4

USB4 is a specification developed by the USB Implementers Forum (USB-IF) to unify and enhance the USB standard. Introduced in 2019, USB4 is designed to run over the USB Type-C connector and to integrate data, display, and power delivery in a single, versatile interface. The specification builds on the Thunderbolt 3 protocol, enabling high performance while remaining compatible with USB-C devices and cables.

The hallmark of USB4 is its maximum aggregate bandwidth of up to 40 gigabits per second, delivered across two 20 Gbps lanes. This bandwidth can be shared flexibly between data, DisplayPort video, and PCIe tunneling as needed. USB4 supports DisplayPort video through alt mode and can tunnel PCIe data, enabling use cases such as external graphics processors, fast external storage, and high-resolution displays. The protocol also supports USB Power Delivery, allowing charging up to 100 watts on capable cables and devices.

Cables and compatibility are a key consideration. USB4 uses USB-C connectors, but not all USB-C cables support the full 40 Gbps or all features; certificated USB4 cables are recommended for maximum performance. Devices with USB4 ports are generally backward compatible with USB 3.x and USB 2.0 peripherals through the USB-C ecosystem, though certain features such as high-speed data or video may require compatible hosts, cables, and peripheral support. Adoption has grown in laptops, desktops, and peripheral devices, with many products shipping USB4 or Thunderbolt 3-compatible ports and accessories.