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PGA900: Sharing bridge for pressure and temperature AFEs

Danilo A.
Mastermind 28590 points
Part Number: PGA900

Hi Team,

We would like to ask your help regarding the customer's inquiry below.

Hi, I am interested in using the PGA900 for conditioning/readout of a piezoresistive pressure transducer. For our application we need to perform both the differential pressure measurement and a temperature measurement (i.e. resistance of the entire transducer) on the same transducer. I was wondering if it's acceptable to connect to the PGA900 this way? Essentially VINPP would be shared with VINTP and VINPN would be shared with VINTN. We would need to turn off the bridge drive on VBRGP when performing the temperature measurement. Could you let me know if you foresee any problems with this approach, or any recommendations?

Thank you for your support!

Regards,

Danilo

  • 0
    TI__Guru**** 180821 points

    Hi Danilo,

    Scott is out until Monday, but in the meantime, I don't immediately see where there would be a problem with this approach.  Do you have a schematic to share with us?

  • +1 in reply to Tom Hendrick
    TI__Mastermind 31655 points

    Hi Danilo,

    Like Tom said, there isn't anything that jumps out as an inherent problem with that approach. Another option would be to include a low temperature coefficient shunt resistor in series with the transducer, and measure the current through both the shunt and the transducer using the VINTN/P inputs to determine the resistance of the transducer. In any case a schematic would be helpful.

    Regards,