USB4 is coming – and most of us still struggle to differentiate between the uncountable types of USB 3 devices, myriad of physical connector types (receptacles), much less the intricacies of features and specifications.
Don’t believe me? Try explaining the difference between USB Power Delivery, Super Speed, 3.0, 3.1 or try telling apart USB A, B, and C from their SuperSpeed counterparts, or accurately identify Mini USB A, B, AB, Micro-A, Micro-B, B SuperSpeed, and Micro AB. You get it, and we haven’t even got to cable compatibility.
Announced by USB Promoter Group just days ago, the USB4 brand now lacks the spacing previous generations of USB had between the brand standard and generation number (USB 2.0, USB 3.0, USB 3.1, USB 3.2). This ostensibly is a change made to consolidate the USB brand name.
While this might in reality only serve to further complicate semantics, USB4 promises to radically improve the ubiquitous standard with a clean slate.
Built upon the Thunderbolt 3 protocol and utilising the USB Type-C form factor, USB4 will support up to 40 Gbit/s (the same as Thunderbolt 3) throughput by utilising two-lane cables, and will be compatible with previous generations of USB like Thunderbolt 3, USB 3.2 and USB 2.0.
First developed by Intel Corporation, Thunderbolt 3’s adoption into the USB4 standard means both protocols will be compatible in most cases.
It also improves in terms of resource allocation for video. A single USB4 port utilised for both video and data transfer will provide better bandwidth allocation, minimising overheads for each process.
One implementation that might particularly find traction is in external graphics processing units (eGPUs). Most examples of eGPUs require the use of Thunderbolt 3, which many laptops lacked support for since it had required the payment of royalties to Intel Corporation.
There’s still a chance that USB4 devices will lack support for Thunderbolt 3, since it isn’t a requirement. However, USB Promoter Group remains optimistic about its support on future devices.
Furthermore, its advertised speeds of up to 40Gbps might not be ubiquitous. USB4 will also be available in 10, 20 and 40 Gbps variants. It remains entirely likely that manufacturers adopt the USB4 standard while scaling back on the actual features it delivers.
The upshot: USB4 could come with top-of-the-line transfer speeds and Thunderbolt 3 support, but only guarantee the ability to allocate resources more efficiently across bandwidth that tops out at 40 Gbps.
Furthermore, USB4 ports will also support USB PD for higher-wattage input and output for charging – up to 100 watts. There’s currently no stipulated minimum power, so the specifications sheet is still king.
Current-gen USB 3.x protocol ports are only capable of splitting resources 50/50 with DisplayPort and data, and is incapable of supporting concurrent data transfer with HDMI alt mode. USB4 will better accomodate multi-use port, a delightful addition given the future of USB-C-only laptops like the MacBook.
When to expect USB4
While recently announced, manufacturers will have to exit their current development cycle before adoption in the next one. This means that we should only expect to see USB4 in ubiquity in about a year or so.
Title Image: Geek Kazu, Flickr