January 23, 2017

How to find a USB-C cable that won’t fry your computer

By Team Ventev Topic: Chargers

USB-C is one of the most promising technologies to come along in a while and is widely expected to replace most of the cables you use, from the one for charging your phone to the one that connects your laptop to your external monitor.

Of course, if you’ve been following the news, you’ve heard of USB-C cables frying a Google engineer’s ChromeBook and other accessories. So you might be wondering: Are USB-C cables safe?

The answer is yes, if they’re certified, or meet the specified standards.

At Ventev, we run our own series of tests to make sure our products perform to our levels of quality and reliability. However, because we design our cables to meet (and generally, exceed) the applicable global standards—USB-C, micro-USB, and Apple (MFi), the cables need to be tested according to the specifications of each particular standard. In the case of USB, this means achieving USB-IF certification standards.

But most people have no idea what this means—or why it’s so important to invest in a cable that has the proper specs. We’re here to tell you how to find a safe cable, and how a certified cable meets the grade.

How bad is a bad cable?

The most high profile example of a faulty cable floating around the Internet was when a USB-A to USB-C connector fried the Chromebook of Google engineer Benson Leung. What happened?

There were two main issues which caused this cable to fry Benson’s Chromebook. First, the Vbus (positive) and GND (negative) wires were backwards, with the positive wire soldered to the negative solder pad, and vice versa. Second, the cable used the wrong valued resistor. 56k is the only value allowed to be used in a USB-A to USB-C cable, but the cable in question used a 10k resistor. A 56k resistor tells the Type C device to discover what the Type A port that it is plugged into is capable of. So if the port in question is only capable of 0.5 Amp, the Type C device knows only to ask for up to 0.5 Amp.

A 10k resistor doesn’t bother to find out what the Type A port is capable of—it just pulls 3 Amps. The 10k resistor can be used when a captive cable is fixed to a Type C charger that supports a minimum of 3 Amps. This means the Type C device can ask for 3 Amps from the charger because the cable is attached to a vendor-specific device, meaning no discovery is needed. The use of the 10k resistor was a major engineering and testing oversight that ultimately caused some real damage to the Chromebook.

These oversights can cause damage to your devices, overheat your cables, or shorten the lifespan of a product that should last much longer. Overall, it’s worth the time to background check the product you’re buying so that you’re not throwing away money in the long run.

So what does certification mean?

Certification means three basic things: Products have met all the standards set by USB, were certified to be compliant to the specification, and were tested for interoperability. The actual tests vary from device to device, depending on the type of product (hub versus cable) and the speed of the device (SuperSpeed, high, or full speed). This earns them one of the following marks on the device itself (note that these are just for cables, not chargers or hubs):

If the cable or packaging has one of the symbols on the left, it means the cable has passed USB certification. USB testing consists of mechanical, electrical, and interoperability testing to make sure the product meets the requirements as well as works well with a number of different devices on the market.

Many of these tests involve using software to pull, push, or otherwise influence the flow of electricity through the device to ensure it works safely and to the standard consumers expect from USB accessories. It can also mean something as simple as testing the strength of the connector, to make sure the wires won’t snap when pulled out of your gadgets.

These testing procedures are upgraded all the time, ensuring that USB accessories are as safe and efficient as possible.

Is my cable certified?

If you’re shopping in person, you can easily keep a look out for the symbols that mark your cable as USB-IF certified. However, buying online can get tricky, as products aren’t always properly labeled. Luckily Benson has taken it upon himself to test out all the USB-C cables he’s come across, so the internet now has a nice handy list of what works properly and what doesn’t (regardless of certification), and the USB website has its own list. Still, there’s a need for a simpler system.

Many retailers (Best Buy, Staples, and Micro Center) have recently committed to only selling USB-IF certified cables, which would make the process easier. Until then, make sure to go through a few extra steps to verify the cable you buy won’t fry your electronics.

And if all else fails, forget the hassle and pick up a Ventev cable—we have the first certified flat USB-C cable and over 20 cables on the USB certified list!

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