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INA3221: Abnormal Register Data (FFF8)

Matt Qi
Expert 4510 points

Part Number: INA3221

Hi team,

My customer faced an abnormal data during the operation. The register is all bit 1.

The detailed description can be as follows:

As above, there will be an abnormal value 4294 on the first channel of two INA3221, and it will return to normal when monitored again after 5 seconds. Hardware signal quality testing found no issues.

The beagle protocol analyzer is used to capture the data as follows.

When an error is found, all the valid data bits in the 01 register are set to 1, and the data is brought into the driver and calculated to be consistent with the actual abnormal value 4294.

Can you help analyze what kind of root cause can introduce this kind of abnormal data?

Thanks a lot.

Best Regards,

Matt.

  • 0
    TI__Mastermind 29955 points

    Hello Matt,

    It looks like your code is not properly handling twos compliment numbers. The hex value 0xFFF8 would actually be a very small negative number, instead of a large positive number. Specifically, 0xFFF8 would be a decimal value of -8. After removing the last 3 bits, the actual shunt value in decimal is -1, which would be just 1 LSB of negative voltage (ie, -40µV)

    Regards,

    Mitch