I have a circuit with 100K thermistor in series with 25k resistor to ground. I connect my adc input to the point where
the thermistor and resistor connect and also a capacitor. This approach works on some adc channels but not others.
reading through the datasheet I notice there is an internal adc resistance of 5k Ras. So it appears having a high impedance input circuit may be an issue.
Is there a reliable way to make this approach work ?
On some of the eval boards like the FRDM-KL03z I notice they use lower value 10k NTC with 5k above and 5k below in series with 2 adc channels. Why do they do this as compared to approach above.