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INA228: Sensor gives no response during EFT test (IEC- 61000 - 4-4). Holding I2C lines

Nikhil Gupta
Prodigy 30 points
Part Number: INA228

Hi,

We are using INA228 sensor for low side DC current sensing using 3mOhm x 3 parallel shunts. We have used appropriate TVS diodes on our DC power rails.

When we are injecting EFT bursts of 1KV, then INA228 stops responding on I2C bus and it continues even if the bursts are removed. We need to restart the system to get it up again.

The INA228 circuit is as shown in figure below : 

kindly suggest what could be the issue and how to resolve.

  • 0
    TI__Mastermind 22595 points

    Hello Nikhil,

    If the is INA228 being communicated with directly during the EFT pulse and communication is interrupted and/or, are there unintended SCL clock pulses during the EFT pulse then it's possible that the communication has been misaligned between the MCU and the INA. This would be why the the INA is not responding as expected and why it is fixed after a power cycle.

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 30 points

    Hello Mitch,

    I2C lines are not getting any issue. There is an EEPROM connected on the same bus. When we are enabling only EEPROM(in firmware) during EFT tests then there is no issue for both read and write on EEPROM and we get proper data without any glitch. But when we enable the INA228(in firmware) then it get stuck. 
    Normally without EFT both the devices are working fine on the I2C Bus.

  • 0 in reply to Nikhil Gupta
    TI__Mastermind 22595 points

    Hey Nikhil,

    Where is the EFT being applied? Also, it would be good to do a test to see if it's a communication issue or device lock-up. For this test you could turn on the Alert pin to something easy/predictable, for example conversion ready flag or a voltage/temperature limit, and see if the alert pin is still activating when you are not able to communicate with it.

    Regards,

    Mitch

  • 0 in reply to Mitch M
    Prodigy 30 points

    Hello Mitch,

    EFT is applied at input source, which is BAT+ and Gnd. I have tested with alert pin, but normally alert pin is working for overcurrent, but during EFT the alert pin doesn't work if overcurrent scenario is emulated. We can clearly see the SCL getting zero/ Gnd latch when EFT signal injected.

  • 0 in reply to Nikhil Gupta
    TI__Mastermind 22595 points

    Hey Nikhil,

    Ok, in that case it looks like you may be latching up the device. From the INA228 datasheet, it looks like we don't have any specs for EFT ratings, so it's hard to say how the device will handle this situation. The closest spec we have are for ESD ratings, which are:

    I recommend adding external protective circuitry for your EFT requirements.

    Regards,

    Mitch