3 ms·
USB-C allows a certain pin to be used for PD negotiation. USB-A doesn't have this pin. USB-A to USB-C cables have a fixed resistor pulling this pin to signal wh
by kuschku 4y ago
USB-C allows a certain pin to be used for PD negotiation. USB-A doesn't have this pin. USB-A to USB-C cables have a fixed resistor pulling this pin to signal which power requirements they support.
Badly designed devices do not negotiate power requirements and just start drawing power, which doesn't work with proper USB-C cables (which expect to negotiate first) but obviously works with USB-A to USB-C cables (which always support the same power requirements)
- steve_adams_86 4y agoThanks for the explanation. This explains all the weird behaviour of devices I have which don’t charge (or charge poorly) over USB C. This was so confusing because I assumed that they should work fine given that they have USB C ports, but no… I’ll have to keep some USB A to C cords around for years still. I just bought a CalDigit element hub and had some hesitation because I thought “how long will I really need the USB A ports?” Evidently they will be handy for quite a while.