The resistance of TMP61 varies from 6k? to 18k? over a temperature range of -40 to 125°C, corresponding to a voltage of 0.45 to 0.9V. The measured voltage range is narrow compared to the ADC input range of -0.2 to 5.5V, so the errors caused by ADC are not very different.

The fix resistor on one of the thermistor pins can be used to calibrate the ADC errors. The resistor with low resistance tolerance and temperature coefficient is recommended to achieve better accuracy.

This document tests the error between the actual and theoretical voltages with different fix value resistances; the results are listed in Table 5-1.

The ADC errors of each measurements do not differ significantly. So the measured voltage can be calibrated by adding the same ADC error of each measurements.