Maybe you're talking about the "Quick Charge 2.0" (& 3.0) protocol, that uses USB protocol to quick charge new smartphones.
It negotiates with host (via USB) to raise USB power voltage to 9V, 12V and 20V.
Using the same current limit and a higher voltage it transfers four times more power.
Quick charge isn't part of the USB spec. It's a bastard protocol pushed by qualcom. It uses the same kind of scheme (odd voltages on the data lines) to indicate charging levels. It isn't "communicated" over USB per se. See here for a interface description http://www.mouser.com/ds/2/328/chiphy_family_datasheet-269468.pdf
. I'd not pursue development here as it's going to go away. Quick Charge was really a stop gap to the USB power delivery spec that we are seeing partially implemented in some USB C devices. The power delivery spec is an official spec and defines power delivery for up to 100W. That said quick charge might be following the PD spec but I'm not certain (haven't researched it and haven't found interface specs for quick charge publicly available).Posted on: August 09, 2016, 06:22:05 18:22 - Automerged
@anotherandrew, yes I am in agreement with you totally manageable with your own design, but possibly not worth it depending if you are developing a product or just doing it for your own edification.