wvmarle:
Parallel to the 10M resistor (i.e. in between your analog pin and GND). The 47M goes in between Vcc and the analog pin.
Thanks for the explanation. Seems to be difficult o find a 47M resistor though (at least on aliexpress)..
but without the MOSFET I'd no longer need to stay below 1V so I could just use 2x 10M and just deal with the 0V-2.75V range
otherwise this kind of impl should also work well enough for my needs - since I am taking no more than 3 measurements an hour..
In any case the feedback in this thread brought my attention to the MOSFET related info that might explain "strange effects" that I had also been experiencing elsewhere..
wvmarle:
10M and 2.2M would have the same effect, just a bit more current (0.4 uA instead of 0.09 uA).
The MOSFET is of course also not perfect, at 30V drain/source there's a 0.1 uA leakage (no data given for the 5.5V you have).
Also don't forget the quiescent current of your regulator, which is also about 1.6 uA.
My sensor currently burns about 80uA in standby mode (I might try to reduce that a bit by replacing the BOD with something like a MAX809S).. but neither of the above would make a significant difference..
