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ADS112C04EVM: Not able to read any temperature

Jonathan Geronga
Expert 7930 points
Part Number: ADS112C04EVM
Other Parts Discussed in Thread: ADS112C04

Hi Team,

I would like to request your input in the situation of our customer regarding his ADS112C04EVM.
The customer cannot able to read any temperatures. He tried both the 800 ohm RTD and a 100ohm RTD. He was using a 1.1kOhm resistor to bridge Ref + and -.

It is his first time using this EVM so your help will be appreciated.

Let me know if you have any questions.

Thanks!

Jonathan

  • 0
    TI__Guru** 113765 points

    Hi Jonathan,

    The ADS112C04EVM user's guide details how to conduct the RTD measurement in section 5.1.1.  Also within the GUI are predefined scripts that can be used depending on the RTD type to setup the EVM.

    As the ADS112C04 uses a voltage reference, the output will not be in temperature.  Instead the measurement can be made ratiometric where the output code returned is based on the reference resistor used.  In this way, the RTD resistance will be (ADC conversion code / total available codes)*Rref / (gain).  Depending on the RTD type there could be an additional factor depending on the number of current sources used to establish the reference.  Once you know the RTD resistance value you can use a polynomial equation or a look-up table to determine the temperature.

    I would also suggest reviewing the applications circuit in the datasheet and A Basic Guide to RTD Measurements.

    Best regards,

    Bob B