USB Implementers Forum (USB-IF) has published USB4 specification, a major update to USB 3.2, after it was announced. The USB4 architecture is based on the Thunderbolt protocol specification recently contributed by Intel Corporation to the USB Promoter Group. The group also has Apple Inc., Hewlett-Packard Inc., Microsoft Corporation, Renesas Corporation, STMicroelectronics, and Texas Instruments, in addition to Intel. USB4 doubles the maximum aggregate bandwidth of USB and enables multiple simultaneous data and display protocols.
The goal for USB4 remains the same with the added goal of helping to converge the USB Type-C connector ecosystem and minimize end-user confusion. USB4 allows for USB data transfers to operate in parallel with other independent protocols specific to display, load/store and host-to-host interfaces. Additionally, USB4 extends performance beyond the 20 Gbps (Gen 2 x 2) of USB 3.2 to 40 Gbps (Gen 3 x 2) over the same dual-lane, dual-simplex architecture.
Key characteristics of the USB4 solution include:
- Two-lane operation using existing USB Type-C cables and up to 40Gbps operation over 40Gbps certified cables
- Multiple data and display protocols that efficiently share the maximum aggregate bandwidth
- Backward compatibility with USB 3.2, USB 2.0 and Thunderbolt 3
USB4 specification provides the host the ability to optimally scale
allocations for display data flow. Even as the USB4 specification introduces a new underlying protocol, compatibility with existing USB 3.2, USB 2.0 and Thunderbolt 3 hosts and devices is supported; the resulting connection scales to the best mutual capability of the devices being connected.