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BQ76952: Temperature coefficient

Nick
Intellectual 682 points

Part Number: BQ76952

I am using BQ769x2 Thermistor Coefficient Calculator to get coefficient for 10K NTC I am using. But temperature is not coming accurate. Ambient is coming 24 deg C but actual is 18 deg.   And at higher temperature offset further  increases.

Sensor data file is attached.

May you have please have look  ?RT curve 10k, 3435.xlsx

  • 0
    TI__Mastermind 42690 points

    Hello Nitin,

    At what temperature ranges are you expecting your device to operate in? I can calculate a set of polynomial coefficients for you, however to obtain the least error, we have to narrow the temperature range. E.g -40C to 90C.

    For a -40C to 90C range I calculated the following coefficients:

    a=[-21846 21845 -1 21845 10922]
    b=[-25001 18724 -7135 4108]

    If you require a different temperature range let me know.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Intellectual 682 points

    My temperature range is -20 to 70 degC. 

    Thanks

  • +1 in reply to Nick
    TI__Mastermind 42690 points

    Hello Nitin,

    I generated these coefficients for you:

    a=[-10923 -1 21845 -1 10922];
    b=[-7944 8701 -4562 3964];
    rc0=11703;
    adc0=11703;

    They're optimized for the -20 to 70 degC, assuming an 18-kOhm internal pull-up.

    Best Regards,

    Luis Hernandez Salomon