I am trying to use the burnout currents for a thermistor measurement, not just sensor detection. The 50uA precision current source is too big to directly measure more then a 50k load with a 2.5v vref. I would like to use the 4uA burnout current source by first passing it through a precision resistor to measure its value on one channel and then using that to measure my thermistor on another channel.
a) How stable is the burnout source? Does it vary based on the load? i.e. would the current source be the same for a 10k load as a 100k load? How about over time? Does it vary over mux channles?
b) do I get a 4uA contribution from both AVDD and from AVSS, thus getting 8uA through my thermistor?