Steve Smith talks about the USB 3 TYPE C cable and the 3A issue related to device power draw.
Episode #7-10 released on November 5, 2016
I'd like to start off with one fact, we have been living for a long time in a relatively safe bubble. USB 1, and USB 2 have been relatively safe technologies up to this day, but with the introduction of USB 3, more specifically with 3 AMP capable Type C connections and devices, we have been introduced to a possible issue that keeps being forgotten.
For the most part, mobile devices that we can power and carry with us have can charge using 1 AMP or even 2.1 AMP charging blocks, USB ports on computers, etc. This is still within the safety limits of your computers, laptops, and other devices. However, USB 3 TYPE C connected devices can pull 3 AMPs to charge faster than other legacy devices. The fact they can pull 3 AMPS means they can, also, pose a serious risk to a whole series of devices if you use the wrong types of cables, and luckily for most of us, a Google Engineer named Benson Leung, has that all explained for us, and I will explain to you the problem, and if you want to see his posts, I will link to them in the show notes.
First, per Benson Leung, USB 3 Type C cables with a 3A resistor terminating in a USB TYPE A, or Legacy USB connector is a problem because the connected device expects to be able to pull 3 AMPs, which will damage the host device. Even using a 1 AMP or 2 AMP chargers won't solve the issue as it continues to be plagued by the same issue. The charging device, because of a badly developed cable, expects a higher output than the host device can deliver. This is because the cable is giving a false signal to the device that makes it believe it can truly pull 3 AMPS, when the host device cannot.
Secondly, the issue does not extend to the TYPE C cables that terminate in TYPE C connectors because they function purely as a pass-through cable, with the device clearly and accurately capable of determining the power capabilities of the host device, so long as it is rated to charge at 3 AMPS like for example a 3 AMP charger you get with Nexus Phones.
Thirdly, if you are going to need a cable that terminates in a legacy connector, you should buy something with a 56K OHM resistor as this will allow the phones, or tablets, or other devices to charge at lower amperages, which will be safer for the host device. This is important because this is the only way to guarantee that the charging device does not attempt to pull more power than the host device can deliver.
Will this problem ever be solved? While, people hate the idea of not having backwards compatibility, the only way to deal with such problems is to render legacy devices and technologies obsolete. Until that starts to occur, it will fall on the consumer to inform themselves on the what they should purchase. Avoiding cheap cables, and making sure you read all available ratings and specifications of the devices and cables you wish to purchase. And, seriously, if you have any worries about cables and chargers to buy, follow the link in my show notes to Benson Leung posts on Google+.
Host : Steve Smith | Music : | Editor : Steve Smith | Producer : Zed Axis Dot Net