AVR-Chat

> Why couldn't you use a N-channel fet at the bottom end of the voltage
> divider, with fairly high resistors for the divider? This would save on
> mosfets and resistors, and I don't think would draw any power when off
> (the AVR's analog inputs are high resistance - 100M according to the
> data sheet). Plus you can use a single fet to switch any number of
> dividers.


Look at the spec for input offset current on the ADC inputs.
They like low impedance sources.  Sampling the input with a low Z
divider looks very practical to me, if the resulting resolution is ok.
Something like 3-4 mV/count?