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INA200: Short Circuit to Battery

Taylor DeSmidt
Prodigy 10 points
Part Number: INA200

Hello,

I am using the INA200 chip as a high side current monitor after the switching FET as shown in the attached schematic.

The issue occurs when we short circuit out1 to battery (27V). We have no issues with a short circuit to ground (which I thought would be the tougher of the two). After the battery short circuit, the INA200 does not read current correctly and we get false faults when a load is attached. If no load is attached, the circuit works okay (no fault). We have replaced the chip and verified it was the chip causing the issue. We added the 220 Ohm resistors (R15 and R16) in series with the sense lines and that let us short circuit up to 30V successfully. We don’t want to increase the resistance too much, as that effects the gain and accuracy of the chip. Any suggestions would be appreciated. We are in the process of monitoring the Vin+ and Vin- lines with an oscilloscope during a short circuit to see what they look like.

  • 0
    TI__Mastermind 30760 points

    Hi,

    Sounds like the faulty device was damaged. Perhaps due to an ESD event? Were there multiple instances?

    In addition to R15/16, I would add a TVS diode (such as 50V) to each pin. They should help with ESD if it is indeed the cause.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 10 points

    Hello Guang,

    I would be very surprised if it was ESD related. It has happened on a few different boards that were built up in house and we follow strict ESD guidelines (dissipative floors, benches, chairs, smocks, etc.).We are able to replicate the failure on multiple units.

  • 0 in reply to Taylor DeSmidt
    TI__Mastermind 30760 points

    Hi,

    It’s good to know that ESD can basically be eliminated as the cause.

    I looked into the return history of this part, and didn’t find a similar failure case. Majority of the past failures were due to ESD damage, or random fab defects which manifest only under certain conditions such as extreme temperatures.

    The fact that a pair of resistors were able to mitigate the issue was leading me to think that the ESD cells might have been compromised. TVS diodes in this case should be helpful in further lowering the risk.

    Regards, Guang