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PGA309 Manually Generated Lookup Table?

Andrew Meier
Prodigy 70 points
Other Parts Discussed in Thread: PGA309

The PGA309 Calibration Spreadsheet is an efficient way to use three sensor voltage output measurements at three temperatures to generate a lookup table that adjusts the zero and gain DACs with temperature.

My question is, does it ever make sense to bypass the Calibration Spreadsheet and manually generate the lookup table?  For example, in correcting not only the sensor response, but also the system that the sensor is measuring?

  • 0
    TI__Mastermind 27715 points

    Hi Andrew,

    The lookup table is typically stored on an external EEPROM or in the memory of a microcontroller/microprocessor. It is not a static table - throughout the calibration process new values are written based on the measured sensor input voltages and the calibration calculations that are performed. There are variations on sensors from the same family (even the same part number!) which require different sets of coefficients to be stored in the lookup table. My manager likes to use the analogy that sensors are like snowflakes; no two sensors are alike.

    For proper calibrated operation the lookup table should not be bypassed. I'm not sure I understand your question about correcting not only the sensor response, but also the system that the sensor is measuring. The input to the sensor is a real-world value, for example, 100 psi. That 100 psi at the input is actually 100 psi, not 97 psi. However, in theory, if any errors in the system at the input to the sensor resulted in error voltages at the output of the sensor, they could be calibrated out.

    Best regards,

    Ian Williams
    Linear Applications Engineer
    Precision Analog and Sensing Products