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Original question:

TAS5411-Q1: FAULT pin of TAS5411

ADS112C04: ADS112C04 Vref

Raymond He
Expert 1990 points

Part Number: ADS112C04

dear

The voltage of PT1000 is read by means of 2-wire design,the voltage value of RTD is read. The external voltage is used as a reference. Do we still need to read the external voltage Vref?

thanks in advance

  • 0
    TI__Guru** 113765 points

    Hi Raymond,

    Are you referring to the 2-wire configuration shown in the ADS112C04 datasheet in Figure 75?  This is a ratiometric measurement where the noise and drift are canceled in the conversion result as the excitation for the RTD and reference is the same.  This also means that the conversion code is proportional to the Rref resistor.  So you do not need to know the exact reference voltage, only the value of the reference resistor.

    I would suggest taking a look at A Basic Guide to RTD Measurements and the 2-wire low-side reference circuit shown in section 2.1 and the calculation for RTD resistance value in equation 18 on page 11.

    Best regards,

    Bob B