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ADS1120: Optimal design to measure four thermistors

Ryan Wagoner
Prodigy 10 points
Part Number: ADS1120

I have the following circuit to measure four 10K thermistors. My plan was to measure them using the external reference so the source voltage wouldn't be a factor in the temperature calculation. However I feel like I should be using the IDAC to power the thermistors to prevent errors introduced by self-heating. I'm taking a measurement from each once per second so they only need to be powered about 5% of the time. Can you provide any advice on the best way to accomplish this?

  • 0
    TI__Guru** 113765 points

    Hi Ryan,

    Welcome to the E2E forum!  There a many ways to measure temperature and a common method does use thermistors.  Thermistor measurements can be done in a variety of ways and voltage excitation is one method.  If I understand your schematic, the thermistors connect to J5-J8 and you will measure the voltage of the thermistor and calculate the resistance value from the voltage divider.  Another possible method is using current excitation relative to a reference resistor similar to an RTD measurement.  You can see those types of configurations in A Basic Guide to RTD Measurements.

    Best regards,

    Bob B