Pogo pins power clarification - reading schematics

[smaeul]

- USB-5V seems like it should always be 5V if PS-5V is enabled and if it has some other voltage when PS-5V is disabled, it's only because there's some remaining charge on the capacitors, or some current going in the reverse direction via U1302 via internal N-MOSFET body diode (see https://megous.com/dl/tmp/06d11858b841c503.png - there's a parasitic diode between S-D in that direction) You're not supposed to rely on USB-5V in this case, when PS-5V is off (another diode on the PS-5V output prevents backfeeding of power through PS-5V)

I believe DC from PS is always allowed to pass through L606 and D600 and charge C645/C646 to the PS voltage. It is only when you want to charge the capacitors to a higher voltage that you need U601 pumping charge out its LX pin. (And in that case, L606 prevents the high-frequency charge pulses from backfeeding into PS.)

It may still be possible for current to flow backward through U1302: if DCIN is at 5V, but PS is at VBAT due to disabling the VBUS path with the sysfs knob mentioned above. It would be interesting to try that and measure the voltage at PIN5.