The USB Implementers Forum (USB-IF) has announced the specifications for USB 4, the successor to USB 3.2. The specifications announced seem to mimic the spec for Thunderbolt 3 and USB-IF is adding another confusion to its name scheme. For starters, it says that USB 4 should drop the space and henceforth be referred to as USB4 but earlier versions will continue to keep the space between their name and the number associated with their specification. The final branding will be announced later but the specifications do seem interesting to begin with.
The USB 4 spec sheet includes dual-lane operation, effective speed of 40Gbps and backward compatibility with existing USB 3.2 and earlier versions of USB, dating back to USB 2.0. The physical connectors will remain the same USB Type-C ones used for Thunderbolt 3, which means all existing Thunderbolt 3 cables should work with USB 4 when it becomes widely available on computing devices. Since there is backward compatibility with Thunderbolt 3, the USB 4 should support the same power delivery options. The announcement made now is a draft version and the final spec is expected to be confirmed by the middle of this year.
The Verge reports that it is expected to take 18 months between the final spec being announced in the second half of this year and the first devices to hit the market with the new USB standard. In other, don’t expect to see USB 4 compliant devices until sometime in 2021. In the meantime, the industry will adopt USB 3.2, which will appear in devices later this year.
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The USB 3.2 will offer dual-lane bandwidth totalling 20Gbps for the full-fat version but there is still some confusion around the branding. It is not immediately clear whether you will get 5, 10 or 20Gbps with USB 3.2 standard. The implementation shows how USB-IF has fallen behind in comparison to Thunderbolt 3, which will be on Apple’s MacBook Pro lineup for good five years.