I'd like to accurately measure the voltage of a battery. My ADC Ref is at 3.3V and my battery is ~5V. I'm looking at not having any quiescent current greater than a few uA's so a voltage divider of 100k is too much of a drain, so I'd like to disable it when not reading it.
I'd like to just use one MOSFET. Would I be able to just use one N-channel MOSFET with a GPIO tied directly to the gate, sitting below a voltage divider, or would I need to have a setup where I use an N-channel to turn on a P-channel by pulling it's gate to ground, as shown in attached image?
Alternatively, are there any concerns with using much larger resistors (800k or so) for this voltage bridge, if I want to leave off the gating?
Thanks!