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INA226: Output current big changes when do RI test in low frequency

Alpha Han
Expert 3750 points
Part Number: INA226

Hi,Team:

My customer Alpine is using INA226-Q1 in BMS project for current sensing. when doing RI test, they find the readout current changes a lot.

When interfere frequency is in 1KHz range, the current changes about +-2A.

When interfere frequency is about 10Hz to 130Hz, when the input current is -8.6A, read out current is about +10A.

The current shunt used is 0.02mohm now. I attached the schematic for your reference. Sorry to say it's not that clear but still can read.

Can you help to advise some suggestion?

  • 0
    TI__Mastermind 21730 points

    Hello Alpha,

    Thanks for reaching out on the forum.  When you say RI, do you mean return-to-inhibit?  Is it possible for you to share an  oscilloscope shot of what they are trying to measure on the INA226 input along with the value the INA226 measured?  Were they able to read the correct values under strictly static DC conditions with no noise?  I ask as I want to make sure that there are no issues with the implementation of the I2C or SMBUS communication protocol.

  • 0 in reply to Patrick Simmons
    TI__Expert 3750 points

    Hi， Patrick:

    Sorry for not describe clearly.

    The RI is part of EMC test according to ISO 11452-8. The test use ”radio coil method“ (I'm not sure if the translate is right or not in English). And the test need to cover 16 2/3Hz、50Hz、150Hz、250Hz、60Hz、180Hz、300Hz, total 7 different frequency.

    You can search ISO 11452-8 spec in website for detailed.

    There is no issue in static condition.

    Thanks.

  • 0 in reply to Alpha Han
    TI__Mastermind 21730 points
    Hello Alpha,

    We do not have any indication in the datasheet that this part is designed for radio interference according to ISO 11452-8 standards, so it is possible that this device is susceptible. To verify that it is just the INA226 device misbehaving, I would shield it with mu metal. If the problem persists, I would remove the INA226 and see if anything else is possibly influencing the data lines.
  • 0 in reply to Patrick Simmons
    TI__Mastermind 21730 points
    Hello Alpha,

    I presume you have found a way to shield the part or are currently investigating alternatives. If you need additional help please me know below. Otherwise, I am closing out this thread.