I'm designing a board with a USB-C upstream-facing port (UFP) for power only (no data). I've included a common-mode choke, as well as a ferrite bead filter in pi configuration. Since I'm presenting as a UFP, I need 5.1 kΩ pulldown resistors on CC1 and CC2.
Should these resistors go before the common-mode choke or after?
In other words, this?
One possible consideration is that I will attach CC1 and CC2 to ADC inputs of an MCU (in order to sense the DFP's current capability advertisement).
I've tried to think through this. If there's no common-mode noise, I think the two options behave basically identically, since the CMC appears as approximately a zero-ohm resistor. If there is common-mode noise, I can't quite wrap my head around which option is less bad, both for the DFP and the MCU.
(Not part of the question, but extra credit for pointing out anything else I might improve with this circuit. I'm considering adding ESD shunt diodes for example.)