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INA237: Issue with the ALERT Pin's unpredictable latching

Hossein Bagherzadeh
Prodigy 10 points
Part Number: INA237

Tool/software:

Hi,

I'm Using the INA237 for a current monitoring and load switching application, I shared the schematics down below, What I'm trying to do here is to configure the INA237 to work standalone and detect the current limit of let's say 8A on the load and when it reaches to the limit, the alert pin is configured to latch a relay which disonnects the load. 

I'm using a host MCU to configure it using I2C and it works for a couple of hours but after that suddenly the alert pin triggers even if the current is not reached the limit. 

The first thing I'm wondering to know is if there is an issue with hardware or the way I'm using it.

  • 0
    TI__Intellectual 2165 points

    Hi Hossein,

    I would recommend you to check the SLOWALERT bit. (Bit 13 of the DIAG_ALRT register)

    If this bit is set low then the alert can be triggered on a single conversion that is too high even though the average value is within spec. Since you are only shown the average value it would appear as if it were a false flag, but if the device is configured in this way you are getting a valid flag. If you only want alert to trigger on the averaged value that you see you should set this bit to be high.

    Some additional notes:

    I am not sure what RE1 is, but if it is an input it could also pull ALERT1 down which would explain your trigger.

    I recommend that you attach VBus to VIn after R17 to get the full effect of the filter.

    Please let me know if this fixes the issue.

    Best,

    Holly