quartz64 model b 2x20 max power

[proj964]

what is the maximum power available on the 3.3v and 5.0v rails assuming only ethernet is attached to the quartz64 model b?

[CounterPillow]

Check the schematic for details.

The 3.3V pins on the GPIO header are fed by VCC3V3_SYS, which is powered from CH2 on the RK809 chip, which is capable of 2.5A of output current. I'd say 2A is a reasonable upper limit to assume for any real world design here.

The 5V seems to go through an SGM40655 over-voltage protection IC, which has a max rated output current of 4.5A. Everything else is derived from this, so I think I'd once again say <1 to 2A is probably a good limit, depending on how much you draw from the 3.3V.

(For situations where anything is plugged into USB, the power available on the 5V rail is obviously going to be impacted.)