USB4 Specification Merges Thunderbolt 3 and USB With Transfer Speeds up to 40Gb/s

The USB4 specification for a new version of USB was today published by the USB Implementers Forum [PDF] giving us details on what to expect from the next-generation USB architecture following a preview back in March.

USB4 is a major update that "complements and builds upon" the current USB 3.2 2x2 (USB-C) and USB 2.0 architectures. According to the USB-IF, the USB4 architecture is based on Thunderbolt, doubling the maximum bandwidth of USB and allowing for multiple simultaneous data and display protocols.


The USB-IF outlined key specifications of the USB4 architecture, such as 40Gb/s speeds (twice the current 20Gb/s maximum) and backwards compatibility with USB 3.2 and Thunderbolt 3.

  • 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 will use the same USB-C connector design as USB 3, which means manufacturers will not need to introduce new USB4 ports into their devices.

Apple's newest Macs offer support for USB-C and Thunderbolt 3, which means most Mac users are already experiencing USB4 speeds when using Thunderbolt 3 cables and devices, but USB4 will make Thunderbolt-style speeds the new default and it will lower the cost of devices that use these faster transfer speeds.

USB Power Delivery will be required in devices built for USB4, which also means we can expect to see higher-powered chargers with multiple USB4 ports.

Though the USB4 specification is complete, it will still be some time before we can expect to see devices that take advantage of USB4. It typically takes at least a year for new products to come out following the finalization of a new specification, so it will be late 2020 or beyond before we begin seeing USB4 devices.

Top Rated Comments

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14 months ago
One cable to rule them all.

Now lets get USB-C on an iPhone.
Score: 49 Votes (Like | Disagree)
Avatar
14 months ago

One cable to rule them all.

Now lets get USB-C on an iPhone.

Don't get me wrong, I like USB-C, but it is not the panacea everyone makes it out to be. There is not "one cable." There are a large number of different USB-C cables, all with different specs, speeds, etc.

Inexpensive USB-C charging cables are limited to USB2 speeds and most of them are limited to 30W of power. There are 60W and higher cables, but in 6ft lengths there are not as many options and it's far from easy to figure out what you're going to get. Some suppliers write the limits in terms of watts, some in terms of volts and amps. Most laymen have trouble figuring it all out.

And then there are the chargers... 18W, 30W, 60W, 90W, 100W, 5V, 12V, 18V, 2A, 3A. Chargers with two ports get even more confusing. While it's relatively easy math, I don't think having people doing Ohm's Law calculations in their heads when buying chargers in cables is user-friendly.

But I mentioned basic charging cables are super slow for data. If you want to use a USB-C cable for data, then it's even more confusing. Speeds vary depending on cable length and spec variant compatibility - a USB-C Gen 1 vs USB-C Gen 2 vs Thunderbolt 3; 1.5ft vs 3ft vs 6ft. Each combination will have a different max speed. It's all very difficult for most folks to keep straight.

Basically, USB is still a spaghetti of specs and limits, and this is just adding yet another layer. Just because the physical plug of Type C is nice, does not mean all the other USB problems are solved.
Score: 33 Votes (Like | Disagree)
Avatar
14 months ago
Congratulations Apple, you were four or five years early—you certainly earn that distinction. Too bad that the products in the meantime were entirely unflexible and annoying for anyone who wanted to conveniently use their laptop as a computer
Score: 16 Votes (Like | Disagree)
Avatar
14 months ago
I don’t even have a Mac with USBC yet..
Score: 12 Votes (Like | Disagree)
Avatar
14 months ago
Will USB4 then drop support for USB-A, B and B's little cousins mini and micro? Because if so, it's about time!
Score: 10 Votes (Like | Disagree)
Avatar
14 months ago
Lightning is still the most robust port design I've ever come across for serious charging/data capabilities. I can plug my phone in every day multiple times a day for two years and the port will still be solid enough to dangle the iPhone from its charging cable no problem. Meanwhile the USB C ports on my MacBook are stupidly loose after just a couple months of use to the point where occasionally the charger would unplug itself if you move the laptop in a strange way.

I know this is controversial but I'd much rather keep a robust port on the iPhone (lightning) than a convenient yet fragile one (USB C).
Score: 7 Votes (Like | Disagree)

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