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Original question:

ADS1261: Excitation current compliance range

ADS1261: ADS1261 excitation current accuracy and stability

Dennis McGlumphy
Expert 1390 points
Part Number: ADS1261


Dear Sirs

I'm using the ADS1261 to do a ratiometric pressure measurement using a bridge type pressure sensor.  I'm using the ADS1261's internal excitation current to power the bridge.  I'm using the amplified voltage drop across a current sensing resistor for the ratiometric reference.  How much does the excitation current accuracy and stability depend on the AVDD.  I will be using a 5vdc LDO for AVDD.  Thank you for your time. 

  • 0
    TI__Guru 54426 points

    Hi Dennis,

    The excitation current sources are derived from the ADC internal reference, which is why the internal reference must be on to use the current sources even if you are not using the internal reference as the VREF source. So the IDAC accuracy and stability are correlated to the internal VREF performance, not AVDD per se.

    Also, if you are using a ratiometric reference, then the IDAC accuracy should not matter too much because any error in the IDAC source should be seen equally in the VREF and the input signal, and therefore cancel out.

    -Bryan