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INA226: How long for ALERT pin to assert after limit is crossed

Zach Kimble
Intellectual 1960 points
Part Number: INA226


Tool/software:

Hello,

I am trying to figure out how long it will take for the ALERT pin to assert after a bus overvoltage event. In the datasheet in section 8.2.1.3, there are two graphs that show an input exceeding a limit and then the ALERT pin being asserted. However, I am not understanding why the time it takes for ALERT to be asserted is 10x longer when the conversion time is 140us when compared to 1.1ms. Can you please explain why it takes longer with a shorter conversion time?

Is there a way to estimate how long it will take for ALERT to assert when using various conversion times?

Thank you!

Best regards,

Zach Kimble

  • 0
    TI__Mastermind 27210 points

    Hello Zach,

    I went over the numbers in those plots, and it looks like they figures are swapped....  The faster conversion time will have a faster ALERT response time. In general, the ALERT response time will depend on the conversion time and how far the threshold is exceeded. When only one channel is enabled, the ALERT response will always be less than 2 times the conversion time. If additional channels are enabled, then add their conversion time to the that value. 

    Regards,

    Mitch

  • 0 in reply to Mitch M
    TI__Intellectual 1960 points

    Hi Mitch,

    Thank you for your quick response! Just to confirm, when you say to add their conversion time to that value when multiple channels are enabled, do you mean add the conversion time for both the bus voltage measurement and the shunt voltage measurement and then multiply that total by 2, or multiply the conversion time for the measurement associated with the ALERT by 2 and then add the other conversion time?

    Also, when you say channels, do you mean just shunt voltage or bus voltage measurement (for this device at least)?

    Have a great weekend!

    Best regards,

    Zach Kimble

  • +1 in reply to Zach Kimble
    TI__Mastermind 27210 points

    Hey Zach,

    Yes, by channels I meant shunt voltage and bus voltage, sorry I should have been more clear. 

    Zach Kimble said:
    multiply the conversion time for the measurement associated with the ALERT by 2 and then add the other conversion time

    This would be the correct way to calculate the maximum alert response time.

    Regards,

    Mitch

  • 0 in reply to Mitch M
    TI__Intellectual 1960 points

    Thank you Mitch! I have no further questions.

  • 0 in reply to Zach Kimble
    TI__Mastermind 27210 points

    You're welcome!