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ADS1014: Is possible to use ADS1014 to detect thermistor

KJ Liu
Intellectual 530 points
Part Number: ADS1014
Other Parts Discussed in Thread: ADS1015

My customer want to use ADS1014 to detect temp of thermistor resistor ?   is it possible without other component to achieve it and what is the schematic looks like ? thanks you very much!

 

  • 0
    TI__Guru**** 168445 points
    Hi KJ,

    When you ask about the ADS1014 for use with a thermistor ‘without other components’, do you mean some sort of amplifier or other active components? Thermistors require some sort of excitation, usually from a constant current source or a voltage source using a reference resistor.
  • 0 in reply to Tom Hendrick
    Intellectual 530 points
    Hi Tom,

    Yes, since the area concern, my customer plan to use VCC as voltage source of thermistor with 1 degree accuracy, per your experience, is it possible ? is the thermal sensor needed for calibration ? I know it's base on accuracy of source and Thermistors. but I wonder to know how to calculate it as evaluation.
  • 0 in reply to KJ Liu
    TI__Guru* 92655 points
    KJ,


    The final accuracy depends on how they have the circuit set up, what temperature range they plan on using, and how they have their excitation set up. Do they have a preliminary schematic or circuit topology? It would be easier to comment on the accuracy of the circuit if we knew what they were planning on doing.

    Any information on how they plan on setting up the schematic would be helpful.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Intellectual 530 points

    The schematic is as below ,

  • 0 in reply to KJ Liu
    TI__Guru* 92655 points

    KJ,

    I still need some more information about the system.

    1. What temperature range do they want to measure? This is important because the thermistor resistance is very sensitive to temperature at cold values or hot values. Even with the linearization resistor, limiting the range may help the absolute temperature accuracy of the measurement.

    2. Is this an NTC or PTC thermistor? Do you have a part number that they intend to use?

    3. How accurate is the 3.3V supply? The resistance measurement accuracy is dependent on the gain error of the ADC, but it is also dependent on how accurate the 3.3V supply. If the 3.3V supply is not accurate, then it may be better to use a 2-channel device like the ADS1015, and make measurements on the 10k resistor and the thermistor, using a ratiometric measurement.

    Joseph Wu

  • 0 in reply to Joseph Wu
    TI__Guru* 92655 points
    KJ,


    I haven't heard back from you for a while. Did you pass along my questions to the customer, or have they been able to find a different solution?

    My concern was that there were many sources of error in making a thermistor measurement, and getting accuracy of the measurement would require more work to identify and reduce the sources of error.

    If your customer has found a working accurate solution, then I'd be happy to review it. If not, I'll wait for responses, but I'll likely close the thread soon. If you have follow-up questions, you can respond with a post. If the thread is closed, start another post.


    Joseph Wu