The Pros and Cons of USB-C

We all know about the classic USB connector, called Standard A or USB-A. We know that no matter which way we turn it, it will be upside down the first time we try to plug it in. Now it’s giving way to USB-C, which has no wrong orientation. Whichever way it’s turned works. The cable uses the same connector at both ends, so you don’t have to hunt for one that matches the device at the other end, the way you do with USB-A.

Slim and versatile

Laptop computers keep getting thinner, and USB-C (or USB Type C) helps them to slim down. The port is just 8.4 x 2.6 mm, compared with 12.5 x 5 mm for USB-A. It’s amazingly versatile in the protocols it carries.

Let’s pause to note the difference between a USB interface and a USB protocol. The interface is the wiring and connection. The protocol is the way data is sent over the interface. USB protocols use numbers rather than letters. USB 2.0 is still widely used. Versions 3.0 and 3.1 improve on it, and there’s even a 3.1 gen 2, with twice the maximum data rate. USB-C can handle all of these.

In fact, it’s designed to handle protocols that aren’t USB at all, using Alternate Modes. They include Display Port, Thunderbolt, HDMI, and MHL. The interface is tremendously versatile — in fact, its versatility is its biggest problem. The cables all look the same, but not all USB-C cables deliver the same functionality. In fact, some of them are dangerous in certain situations.

One size, but not all fit

USB power delivery — the full specification, not the limited power which is more widely available — can handle up to a hundred watts. Some but not all USB cables support it. Trying to get 100 watts through a cable not designed for it could do bad things. USB 3.1 gen 2 can deliver 10 Gbps, twice the maximum of gen 1. Not all cables handle the higher speed, and attempting it on a cable that doesn’t will lead to frustration.

Then there are the cables which are just cheaply made. This has always been a problem, but with the many ways USB-C works, it’s more likely than ever to cause trouble. A bad cable can even burn out a device. Device manufacturers have always warned us to use only their cables, and we’re used to thinking of their words as just a marketing tactic. With USB-C, we should take the warnings more seriously.

Using the cables for USB data transfer doesn’t pose a lot of problems, if you aren’t trying for 10 Gbps. Chargers and alt mode connections are the source of the large majority of problems. Engadget reports that alt mode docks are “extremely inconsistent.” The various alternate modes are all specified by different organizations, and there’s no requirement that a USB-C device support any of them.

The alternate modes aren’t always full implementations of the latest standards that they bridge to. Alt-mode HDMI is based on HDMI 1.4b, which is behind the current HDMI 2.0b.

Consumers are used to assuming that if a cable plugs in, it should work. With USB-C, that’s not a safe assumption.

The future of USB

Whether we like it or not, USB-C is inevitably replacing the ancient USB-A interface. Over time, it will replace the confusing variety of mini, micro, and other connectors on peripheral devices and phones. As the standard becomes more widely adopted, the compatibility issues will diminish, at least among the reputable brands.

For the present, USB-C is an exciting advance, but consumers will have to be more careful than usual about the cables they use. Top-quality cables should work for all purposes, but using a cheap one could mean getting literally burned.

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