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LP3879: Is it normal that NC(pin2) short to GND (pin3)

Robin Yu
Intellectual 2190 points
Part Number: LP3879

Hi team,

It is found by customer that pin2 and pin3 are short together for some new LP3879 devices.

4 among 30 is found this problem. It is tested  for only chip.

Is that normal?

Thanks.

Robin

  • 0
    TI__Guru 55940 points

    Hi Robin,

    Pin 2 is used for post package testing and is not meant to be driven by the customer at anytime.  Please provide a scopeshot of Vin, Vout, V/shutdown, and Iout in order for us to help debug.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    TI__Intellectual 2190 points

    Hi Ryan,

    From customer feedback, there is no output for the failed chip.

    Just to want to confirm if it is normal for the very low impedance between these 2 pins for only chip test.

    Thanks.

    Robin

  • 0 in reply to Robin Yu
    TI__Mastermind 23361 points

    Hi Robin, 

    I was planning to take a look on bench, but we don't currently have LP3879 in house. As Ryan mentioned, Pin 2 is used for programming and must be left floating. This may or may not be directly related to the failures that customers had found. 

    In order to help identify the reason for the failures, we would need to have more details on the tests customers did that caused the failures. If you could ask them to provide us with scope-shots that may be related to the failures, it would be very helpful. 

    Regards, 

    Jason Song