The USB Implementer's Forum (USB-IF), responsible for creating USB specifications, today published the USB4 spec. Besides removing the space from its naming system, USB4 offers twice as much bandwidth as USB 3.2, resulting in a maximum throughput of 40 Gbps when using appropriately certified cables.
USB-IF announced the USB4 spec in March. In addition to increased throughput, USB4 offers "the ability to optimally scale allocations for display data flow," which makes it possible to daisy chain devices even if they're a mix of external displays and data-driven devices, like external storage. The next-generation USB interface will also be backwards compatible with USB 2, USB 3.2 and Thunderbolt 3.
|Specification||Throughput||Previous Term||Technical Term||Marketing Term|
|USB 4||40 Gbps||N/A||USB 4.0||Not Announced|
|USB 3.2||20 Gbps||N/A||USB 3.2 Gen 2x2||SuperSpeed USB 20Gbps|
|USB 3.1||10 Gbps||USB 3.1 Gen 2||USB 3.2 Gen 2||SuperSpeed USB 10Gbps|
|USB 3.0||5 Gbps||USB 3.1 Gen 1||USB 3.2 Gen 1||SuperSpeed USB|
The backwards compatibility with Thunderbolt 3--along with some of the improvements made to USB4 as a whole--results from Intel contributing its Thunderbolt technology to the USB specification. That means Thunderbolt-compatible products will no longer have to pay the company a licensing fee, too, which should incentivize manufacturers to adopt Thunderbolt in their products sooner than later.
USB-IF plans to announce a new specification for the USB Type-C connector to handle USB4 bus delivery (the backwards compatibility wouldn't mean that much to most people if they had to deal with yet another connector type). The group plans to reveal more about its plans for USB4, USB Type-C, USB Power Delivery and "new USB-IF branding strategies" at the USB Developer Days conferences in Seattle and Taipei later this year.
Check out our summary of everything we know about USB4 for more information.