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ADS122C04: Sensor output voltage 0.5-4.5V. Need to change Vref ?

Joel Johera
Prodigy 10 points
Part Number: ADS122C04

Hi,

I am designing a circuit where a pressure sensor that its ouput goes from 0.5v to 4.5v. But I do not know if I have to change the reference voltage to 5v or I can use the internal one.

In case I have to change the reference voltage I just need to apply +5V to REFP and GND to REFN ?

Thanks for your time.

  • 0
    TI__Mastermind 20805 points

    Hi Joel,

    welcome to our e2e forum and thank you for your interest in our ADS122C04.

    The easiest solution would be to use an external 5V voltage reference in this case. As you correctly stated, you would connect REFN to GND and REFP to the 5V reference.

    There is a potential way to use the internal reference, but it will likely not be as accurate. With the internal 2.048V voltage reference you can measure differential voltage swings of +/-2.048V. Means if you would have a very stable 2.5V signal in your system, you could connect AINn to the 2.5V bias voltage and AINp to the output of the pressure sensor.

    • When the pressure sensor outputs 0.5V, the ADS122C04 would then report -2V as a conversion result
    • When the pressure sensor outputs 2.5V, the ADS122C04 would report 0V as a conversion result and
    • When the pressure sensor outputs 4.5V, the ADS122C04 would report +2V as a conversion result

    However the accuracy of the measurement would depend on the accuracy of the 2.5V bias voltage.

    Regards,