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PGA300: Zero / span trimming with potentiometers for 4-20mA applications

Gaurav Hirlekar
Prodigy 90 points
Part Number: PGA300

The PGA300 datasheet describes a 4-20 mA application.
However, I cannot see any way to trim the output zero and span using multiturn potentiometers.

I'd be grateful if you could suggest a solution.

  • 0
    TI__Mastermind 31655 points

    Hi Guarav,

    The output is calibrated through the internal compensation engine. Please refer to the Temperature and Nonlinearity Compensation section of the datasheet that describes this. Even if the temperature compensation is not needed, a 3 pressure 1 temperature calibration can be done that will account for the offset and span trim of the 4-20mA output. If you haven't already, you can try this yourself by using the PGA300 GUI to generate the calibration coefficients that are programmed into the PGA300's EEPROM. This can be done through the ADC and DAC calibration page, or by using the Guided Calibration page.

    Regards,

    Scott

  • 0 in reply to Scott Cummins
    Prodigy 90 points

    Dear Scott,

    For factory calibration, I agree with what you say.
    However, for field trimming of zero and span (for sensor aging, installation effect, etc.), we need to provide multi turn trimmer potentiometers that can trim the zero/span by up to +/- 5%.
    The application will be purely analog, so there will be no microcontroller on board to flash the new calibration coefficients on the PGA300 once it leaves the factory.

    Regards,
    Gaurav

  • 0 in reply to Gaurav Hirlekar
    TI__Mastermind 31655 points

    Hi Gaurav,

    If you mean to trim the sensor connected to the pressure inputs, then it will depend on the type of sensor you are using. There would be no problem with including some trim potentiometers, but of course they would need to be in place during the factory calibration.

    Regards,
    Scott