I am looking to power homebrew computer designs with USB-C. I have previously used USB-B micro at 5v and the current limits there haven't been a problem but when building analog circuitry (a sound card for example) being restricted to 5V single-supply op-amps is limiting. So I have been investigating the feasibility of using USB PD with the following requirements:
- Sink only, this computer will never source, only sink current
- USB 2.0 data transfer. I want a single port (USB-C) connected to a host computer for power and usb-to-serial data over D+/D- so data must go both ways
- higher voltage so I can create a more reasonable dual-supply (+- 10V from 20V maybe? Ideally +- 12V from 24V but I don't believe this is officially part of the PD spec.)
- current shouldn't be a problem, I don't think I will get close to 3A
According to this Texas Instruments primer on USB-C this should be possible. See header "USB Type-C DRP/DRD: USB 2.0 with USB PD". But in searching for an IC to do PD negotation for me, I don't ever see references to D+/D- in conjunction with PD.
So my question is are there example circuits for this kind of scenario? Are there good ICs for PD negotation and/or USB 2.0 data transfer? I looked at the barrel-jack replacement series (CYPD3177) which is used in decoy boards a lot but those are always for power, never data transfer but if the two concepts are separate, I would love to know about it.