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INA303: ALERT status falsely changing to low

Bart
Expert 6420 points
Part Number: INA303

Hello team,

we use INA303 for current shunt measurement. Sometimes when measuring voltage at the battery (or other points in the circuit), the ALERT pin falsely changes its state to low - the current does not flow and due to the fault condition it thinks there is overcurrent event.

Is there any way to mitigate this? The issue is that ALERT needs to be reset to make the power circuit operable again.

Below the schematic (the pull up resistor is not visible and placed elsewhere, 10k to 3.3V).

Thanks for the support.

  • 0
    TI__Mastermind 31580 points

    Hi,

    Does the false trip happen during normal operation or transient state such as power on/off? Are you able to tell which comparator was tripped? You could slightly increase the input filter RC value to see if it is a noise issue. Increasing the limits setting resistors will also help if acceptable.

    Another question - does the battery/load circuit share the same ground as INA303?

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 40 points

    Hi,

    False trip occurs during normal system operation. This usually happens when measuring the voltage of the battery with a multimeter.

    I don't know which limit has been exceeded. How can I check it?

    Will it help to add capacitors between IN +, IN- and GND?

    We cannot increase the resistors from the limit.

    Yes, the ground of the battery and the ground of the INA303 are connected to each other.

    Regards,
    Kamil

  • 0 in reply to Kamil Pilka
    TI__Mastermind 31580 points

    Hi,

    It does sound like a noise issue. As you suggested, adding a pair of capacitors to ground might help. Replacing R9/10 with ferrite beads might help further. These are some of things you could try.

    To find out which comparator trips would require disconnecting the two Alert pins, one at a time.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 40 points

    Okay, I'll try to apply capacitors to GND.

    Can you suggest ferrite beads that I could use here? What impedance should ferrite beads have?

    Elsewhere in my project, I'm already using 600 Ohm ferrite beads, 100 mOhm for DC signal - ILHB0805ER601V.


    Regards,

    Kamil

  • 0 in reply to Kamil Pilka
    TI__Mastermind 31580 points

    Hi Kamil,

    I would just go with the one you already have as an experiment, and worry about accuracy implications if it proves to be helpful stabilizing the system.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 40 points

    Hi Guang,

    Thank you for your help. I will try to apply these hints in my system.

    Regards,

    Kamil

  • 0 in reply to Kamil Pilka
    TI__Mastermind 31580 points

    Hi Kamil,

    Sounds good, please keep us posted on your progress/results.

    Regards, Guang