USB C charger power negotiations

Thread Starter


Joined Feb 22, 2021
Ok so this may be better suited for the power electronics thread but it has to do with communication so idk

I am trying to learn about USB C chargers. I understand USB A chargers as they use command resistors on the data pins to tell whatever device how much current it can draw/that this charger is a genuine charger. I have also found that simply bridging the data pin will allow an iphone to charge at around 1A.

Is there something similar for USB C? Every time I try to find more information about this it tells me the same thing and then tries to get me to buy chip to do all the negotiations.

I am trying to get it so that the usb C only charges at the about 1A(900mA) as per the 3.1 standard or at most 1.5A. I know some devices require more than this but that is the limit of my design. Plus I have seen some USBC chargers that are rated at 5V 900mA
thank you