Thunderbolt 3, USB C and USB 3.1

Admin Estimated Read Time: 2 Minutes

Thunderbolt3 is the most popular high-speed interface today and its capabilities go beyond just data transfer - you can daisy chain devices, connect displays, and deliver power at the same time. 

Since both Thunderbolt3 and USB 3.1 use the same USB C Connectors, some confusion ensues which we intend to clarify in this article.

USB C is just the connector Type, used by both USB 3.1 and Thunderbolt3

USB-C ( or USB Type C) is the physical connector - The shape of the connector itself and the way the pins are laid out and connected together. USB-C Connectors are used for USB 3.1 and also Thunderbolt3. Just like earlier Thunderbolt used Display Port, thunderbolt3 uses USB-C Port. 

There is no way to tell if a USB C Port is for USB 3.1 or Thunderbolt3, just by looking at it, that's why a sign is put next to it to indicate if this is a thunderbolt or USB Port. 

Look at this LaCie d2 device for example that has USB 3.1 and Thunderbolt3 ports, both with the same connector. There is no way you can tell them apart without looking at the symbol of USB and TB next to the port.

ABCD

Since the port is visually and physically the same, there is nothing that warns/prevents you from Plugging in a USB 3.1 cable and device to a Thunderbolt3 port, though it won't give you the Thunderbolt3 speed, since Thunderbolt3 has USB 3.1 specifications built-in. In contrast, a Thunderbolt3 device can't be used with a USB 3.1 port.

  • Thunderbolt 3 Device -> Thunderbolt 3 Port - > Full Speed ( Upto 40Gbps)
  • USB 3.1 Type C Device - > Thunderbolt 3 Port -> USB 3.1 Speed ( Upto 10Gbps)
  • Thunderbolt3 Device -> USB 3.1 Type C port -> NOT COMPATIBLE

Cables look the same, but they are slightly different

Since the pin configuration on both USB 3.1 type C and Thunderbolt3 are the same, all the USB C cables SHOULD work with your Thunderbolt3, except they sometimes don't. 

  • If your USB 3.1 ( Type C) cable is short length and good quality, it may work with Thunderbolt3, but may not give you enough speed
  • If your USB 3.1 Type C Cable is long, it will mostly not work with Thunderbolt 3
  • Your best bet is to buy a Thunderbolt 3 cable for Thunderbolt 3 devices ( like Belkin thunderbolt 60W or 100W cable). They are expensive but they always work with thunderbolt
  • If you want a Thunderbolt cable longer than 1 meter, go with an Active ( powered) cable. Passive cables can't give you full speed without using power to boost the signal. However, the only cables we have been selling are short length Passive cable. ( Belkin 0.5m is the pick most of the times)

If you have any questions or comments, feel free to ask in the comment section.

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