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BQ76952: How to calculate the coeff of 18K Temperature model?

Statham Su
Genius 4990 points
Part Number: BQ76952

Hello Sir:

I want to know that how to calculate the coeff of 18K Temperature model? 

I know there is a calculation tool, but I want to know the formula.

Can you provide a formula to explain the coeff a1~a5, b1~b4 and Adc0?

Thanks a lot.

  • 0
    Genius 4990 points

    Hello Sir:

    The other we should be followed the calculation results of excel file and fill to 18K Temperature Model of DF.

    Or we should be used the default value of 18K Temperature Model of DF.

    We saw the default value of 18K Temperature Model of DF is not the same with calculation results of excel file.

    Which one should we select?

    Please provide us the recommendations.

    Thanks a lot.

  • 0
    TI__Guru* 81034 points

    Hi Statham,

    Due to the complexity of the calculations and their use of internal trim information, we do not publish all the detailed calculations that are performed using the polynomial coefficients to calculate the reported temperature.  We recommend you use the provided spreadsheet to select coefficients based on your specific thermistor.  If this does not meet the accuracy you need for your system, you might consider adding a further adjustment to the reported values in your host processor software, before using the temperature value.

    If you are using the Semitec AT103-2 thermistor, you can use the default values for the 18K temperature model. This is what was used for the data collected in the datasheet plots and gives good results. The spreadsheet tries to factor in the pad resistance and adjusts the resistance of the internal pullup, but the device was characterized using the defaults before these adjustments were made.

    Best regards,

    Matt