USB-IF publishes USB4 specification

Specification now available for download on USB-IF website; doubles bandwidth to extend USB Type-C performance.

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The USB Implementers Forum (USB-IF - Beaverton, OR), the support organization for the advancement and adoption of USB technology, on Sept. 3 announced the publication of the USB4 specification, billed as “a major update to deliver the next-generation USB architecture that complements and builds upon the existing USB 3.2 and USB 2.0 architectures.”

The USB4 architecture is based on the Thunderbolt protocol specification recently contributed by Intel Corporation to the USB Promoter Group. It doubles the maximum aggregate bandwidth of USB and enables multiple simultaneous data and display protocols. The development of the USB4 specification was first announced in March 2019 by the USB Promoter Group. It is now officially published by USB-IF and available for download at

Key characteristics of the USB4 technology 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

As the USB Type-C connector has evolved into the role as the external display port of many host products, the 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.

The upcoming USB Developer Days 2019 will include detailed technical training covering the USB4 specification and the latest for USB Type-C, USB Power Delivery, and new USB-IF branding strategies. Event details are as follows:

• USB Developer Days – Seattle September 17-18, 2019 Grand Hyatt Seattle, Seattle, Washington, USA

• USB Developer Days – Taipei November 19-20, 2019 W Taipei, Taipei, Taiwan About USB-IF

Registration information for the above opportunities is available at


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