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INA303: Is it authorized to set LIMIT1 below LIMIT2

Simon Lassier
Prodigy 10 points
Part Number: INA303

Hi everybody,

I would like to verify with you if it is possible or not to set LIMIT1 below LIMIT2 in an INA303Ax. It do not seems forbidden regarding the output comparators which seems quitte independent but I want to be sure it won't reduce lifetime or anything else.

I'm measuring a bidirectional current and LIMIT1 will be set on a negative current value & LIMIT2 on a positive current value.

Thanks for your help.

Simon

  • 0
    TI__Expert 4720 points

    Hello,

    The comparators are connected differently. Meaning if you set limit 2 above your operating current you will always alert, in the INA303 limit 2 is an under limit. if you set limit 1 below your operating current you will always alert, in the INA303 limit 1 is an over limit.

    So I would suggest you have limit 2 set on a negative current value. And limit 1 on a positive current value.

    This is because (for example) Vs = 3.3V and Ref = 1.65V. Set limit 1 = 2V and set limit 2 = 1.3V. When you get positive current your output will be 1.65 + current*Gain*Rshunt. lets suppose this is 2.5V you will alert on this with alert 1. When you are sensing negative current Vout = 1.65 - current*Gain*Rshunt. Lets suppose this is 1.25V you will now alert on alert 2. Therefore will achieve your desired outcome.

    Regards,

    Cas

  • 0 in reply to Castrense Nigrelli
    Prodigy 10 points

    Hi,

    I agree my application is quite special, I do need ALERT1 below ALERT2, even if it mean ALERT2 & ALERT1 will be at the low level simultaneously in some cases.

    However, what I want to be sure is the internal possibility do configure the INA303 with ALERT1 below ALERT2. Does it exist an internal limitation or component which forbid this configuration ?

    I tried this configuration on a demo board and it seems working. The ALERT1 & ALERT2 toggle independently and without overheating or anything else.

    Regards,

    Simon

  • 0 in reply to Simon Lassier
    TI__Expert 4720 points

    Hello,

    If you do not violate the abs max on the INA then there should not be a problem.

    Regards,

    Cas