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ADS1271: Behavior above specs.

Jose Tamez
Prodigy 30 points

Part Number: ADS1271
Other Parts Discussed in Thread: ADS127L01

I have an application using the ADS1271 ADC, the inputs come in a true differential form.

Occasionally the values might exceed the analog limits, the ADS1271 has a 5V power on AVDD and a reference at 2.5V. The inputs will some times deviate up to +/-3V giving a 6 volt differential for a very short time.

I expected the ADC to clip the values at 7FFFFFh and 800000h, but it is not.

Is this to be expected because of the signals going out of specs briefly?

  • 0
    TI__Guru 51610 points

    Hello Jose,

    Yes, when the input differential voltage exceeds the maximum +/-Vref range by several percent, the internal modulator can saturate and go through a reset.  This will produce random looking data.

    ADS127L01 is the next generation version of the ADS1271 and includes an out-of-range detector, which sets a bit in the status word to let you know when the input is in an over range condition.

    Regards,
    Keith Nicholas
    Precision ADC Applications