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BQ76952: BQ76952 measuring voltage difference

DILEEP SINGH
Intellectual 340 points
Part Number: BQ76952

Hi Matt,

Please let me know why pack pin voltage & Load pin voltage are differ as both are sensing from same point. And Why are there 1 cell voltage difference between top of stack voltage & Cell sum voltage ? Similarly load pin voltage is also grater than pack voltage with value of equivalent to 2 cells.

  • 0
    TI__Guru 54715 points

    Hi Dileep,

    The BQ76952 has internal selection switches and divider resistors to scale the top of stack, PACK pin and LD pin voltages.  Connection resistance will vary, so the pins are not calibrated at the factory and these will need to be calibrated on the board.  The pre-production parts may not perform as well as the final devices as there have been refinements made during the release process. 

  • 0 in reply to WM5295
    Intellectual 340 points

    Hi,

    I have purchased BQ76952 active part, but still it is showing difference in cell sum voltage & stack voltage, Load voltage & Pack voltage. I am not able to understand why pack voltage & Load voltage are not same as hardware is same for both pins and gain, calibration, offset everything is same. but still measured value is not the same why ??

  • 0 in reply to DILEEP SINGH
    TI__Guru* 77353 points

    Hi Dileep,

    The Stack, Load, and Pack voltages will show small differences if you do not calibrate these measurements. You can read about how to calibrate these in the BQ76952, BQ76942 Calibration and OTP Programming Guide. These measurements use different circuits in the device.

    If you are seeing very large differences between the stack voltage and the other two voltages, it could be because you have not enabled the FETs. Try clicking the 'FET_ENABLE' button in the commands window and the SLEEP_DISABLE button. Then click Refresh once or twice to see if the measured values update.

    Best regards,

    Matt