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Original question:

BQ76952: Current and Voltage Measurement Accuracy

BQ76942: sample current accuracy

Jingguo Wang
Intellectual 2580 points
Part Number: BQ76942

Hi team, Customer want to calculate the sample current accuracy, the calculation result is 0.018A and the actual error is 200-300mA at 100A.

Could you help to check the if the calculation method is right?  they use CC2 and CC3.  the calculation process is as follow.

  • 0
    TI__Mastermind 42060 points

    Hello Jingguo,

    I do not speak Chinese. So it is hard to know exactly what is being done here. Can you please translate this?

    However, I do notice they seem to have a 50-uOhm sense resistor. 1-LSB is ~7.6-uV. Offset error is 1LSB, so 7.6-uV/50-uOhm = 0.152-A. So even if there were to be no current, it is possible to read a value between +/- 152-mA.

    Additionally, this is the resolution of the current measurement (152-mA). So the current would only change in 152-mA steps.

    If they take a log of the current, is this the case? Using CC3 should be able to filter out some of the offset noise. 

    Best Regards,

    Luis Hernandez Salomon