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LM20: Worst-case accuracy at -40C

Steve Widener
Genius 11010 points
Part Number: LM20

From the datasheet, the LM20BIM7 is specified at +/- 2.3C accuracy at -40C but this is at a fixed Vs of 2.7V.

Please provide guidance on how to combine the line, load and linearity specifications to attain a total worst-case temperature accuracy for this device

Please also provide guidance on the long-term stability for the device (end of life tolerance).

  • 0
    TI__Expert 7855 points

    Hi Steve,

    Allow me a few days to work on this.

    -Kelvin

  • 0 in reply to Kelvin Le THS
    TI__Expert 7855 points
    You don't have to add non-linearity error since this is already included in the device accuracy spec.

    Example error calculation for Vs=3.3V, T=-40C

    Note: The accuracy is specified with Vs=2.7V so this is your reference point. Assuming-11.77mV/C as the gain.

    Line error (max) = (3.3V-2.7V)*3.3mV/V = 1.98mV = 1.98mV/-11.77mV/C = -0.168C

    Load error (max) = -2.5mV => -2.5mV/-11.77mV/C = 0.212C (IL=0uA to 16uA)

    Device error at -40C = ±4.8C (in datasheet)


    Total Worst Case* = |Device|+Load error+Line error =4.8+0.212-0.168=4.8C.

    This doesn't account for ADC contribution yet so the total error should be

    Total Worst Case = Total Worst Case* + ADC_error(T=-40C)


    With respect to drift you can use this:

    www.ti.com/.../estimator.tsp

    and this post for drift discussion

    e2e.ti.com/.../637702

    basically we expect the device to performance within spec for 8 years with 60% confidence.

    -Kelvin