I really am not very concerned with speed.

Something around 50 times per second is probably more than adequate.

I am in the US so I want to avoid 60Hz for obvious reasons.

I will attempting to read the resistance on of a precision multi-turn(10) potentiometer.

I need a reliable, repeatable measurement of better than 1 part in 8000.

With 13 bits (8192) that might be just within realm of possibility.

Actually I plan to read both sides by applying a reference voltage (V0) to the wiper and then reading the output on both sides (V1 and V2).

Thus X1= (V1)/(V1+V2), X2 = V2/(X1+X2), X0=X1+X2 ... looks very much like a voltage divider but it is not ... totally mechanical

X0 is known and fixed (

*i.e. X always = 8000*). Thus whatever value comes out, it is scaled such that X0=X.

I may need to a 20 or 24 bit ADC to the achieve what I am looking for but the concept of being able use an internal ADC is very appealing.