What you need to know about USB-C

Many new devices are starting to sport the new “USB-C” (or USB Type C) ports.  These ports are different in almost every way from previous generations of USB ports and devices.

Traditionally "USB" referred to the port, the cable, and the protocol being used over them.  While over the years there have been several different versions of USB ports (USB 1, USB 2, USB 3) and cables (micro, mini, etc), they all used the same USB protocols.  Using these USB devices was fairly painless, and cabling worked on the "if it fits, it works" theory.

With USB-C, that changes.  USB-C refers to the port and a variety of supporting cables.  While all the cables have the same 24-pin reversible plug,  they can have drastically different capabilities and characteristics.  But the real change comes in protocol: USB-C ports can support multiple protocols and functions, such as the USB, DisplayPort, HDMI, and Thunderbolt protocols, as well as functions like Audio Accessory Mode and delivery of up to 100 Watts of power to connected devices.

This can cause some confusion and performance issues with USB-C, as not every USB-C cable, port, device, and power supply will be compatible; or they may be limited in some way.  Worse, vendors tend to make all the cables look so similar that you can't easily distinguish between them.  For this reason, you must be very careful to buy the proper USB-C cable for your application, and to label (or color code) it somehow so you know which cable is for what –-- otherwise, you risk using the wrong cable and its either not performing correctly, not working at all, or perhaps even damaging your equipment!

The next issue to watch out for is the number and type of ports on a device.  Some new devices ship with only USB-C ports, and no other port types!  This seems fine, except you need to make sure that you have enough ports for your needs.  Also, if you need a connection not supported by USB-C (such as ethernet) you will need some kind of USB-C-based dongle to provide that function.  And if you have older devices that require older cables, you'll need adapters or dongles to support those, as well  (e.g., a USB-C-to-USB-3 cable).

Last, we should note that while Thunderbolt 3 and USB-C can use the same physical port, Thunderbolt requires a totally different cable.  While a Thunderbolt 3 cable should be able to do USB-C, a USB-C cable can not do Thunderbolt 3!  So be sure to buy the correct cable.  Also, Thunderbolt 3 is not the same connector as earlier Thunderbolt connectors; therefore, if you want to use older Thunderbolt devices, you will need a Thunderbolt-3-to-Thunderbolt-2 adapter or dongle.

Written by Eric Rostetter, Senior System Administrator
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See also: Hardware