Next-generation USB is nearly upon us, and it promises to be speedy. The USB Implementers Forum (USB-IF), the not-for-profit organization created to promote and support the USB standard, today unveiled USB4, which it says will be capable of achieving speeds upwards of 40Gbps over certified cables — twice the maximum speed of the current specification, USB 3.2.
To achieve that feat, USB4 introduces a new underlying transfer scheme that taps two lanes (using existing USB Type-C cables) and supports multiple data and display protocols that “efficiently” share the total available bandwidth over the bus. (That’s roughly enough throughput to power two 4K displays, a single 5K display, or an external graphics card.) It’s backward compatible with USB 3.2, USB 2.0, and Intel’s Thunderbolt 3 technology and will be able to deliver up to 100W of power.
“The primary goal of USB is to deliver the best user experience combining data, display, and power delivery over a user-friendly and robust cable and connector solution,” said USB Promoter group chair Brad Saunders. “The USB4 solution specifically tailors bus operation to further enhance this experience by optimizing the blend of data and display over a single connection and enabling the further doubling of performance,” he added.
USB4 shares more than a few characteristics with Thunderbolt 3, which already supports the simultaneous data transfer and speeds of up to 40Gbps. But, crucially, Thunderbolt 3 is proprietary; Manufacturers are required to obtain certification in order to support it. (It is now royalty-free, however.) By contrast, USB4 is an open standard.
That’s a double-edged sword, of course. While USB4 might be more broadly implemented than Thunderbolt 3, it likely won’t be consistently implemented, because the USB-IF doesn’t impose mandatory requirements on adoptees. It’s up to each company to choose which features to build in.
That’s why Intel isn’t likely in a hurry to ditch Thunderbolt 3, which currently features in the designs of over 400 PCs and 450 docks, displays, external graphics enclosures, and storage from HP, Apple, Asus, Lenovo, Dell, and Huawei. The company points out that its program offers reference designs and technical support in addition to documentation.
“Releasing the Thunderbolt protocol specification is a significant milestone for making today’s simplest and most versatile port available to everyone,” said Jason Ziller, general manager at Intel’s client connectivity division. “By collaborating with the USB Promoter Group, we’re opening the doors for innovation across a wide range of devices and increasing compatibility to deliver better experiences to consumers.”
The USB-IF and the 50 companies actively participating in the USB4 drafting process are working toward finalization ahead of the USB Developer Days conference in Vancouver, where additional information about the new standard (along with USB Type-C cable and USB Power Delivery) is expected to be released.
The news comes after the USB-IF announced a rebranding of USB 3.0 and USB 3.1 that folded them together under USB 3.2. With that move, USB 3.1 Gen 1, which has transfer speeds up to 5Gbps, became USB 3.2 Gen 1, while USB 3.2 Gen 1, which can reach speeds of up to 10Gbps, is now USB 3.2 Gen 2. Each got a confusing new marketing term: USB 3.2 Gen 1 is SuperSpeed USB; USB 3.2 Gen 2 is SuperSpeed USB 10Gbps; and USB 3.2 Gen 2×2, which can hit speeds of 20Gbps, is SuperSpeed USB 20Gbps.