USB C charger power negotiations

Thread Starter

jlawley1969

Joined Feb 22, 2021
97
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
 
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