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LM2936 output pin shorted to ground

Sanjib Baral
Prodigy 20 points
Other Parts Discussed in Thread: LM2936

We use above circuit to generate regulated voltage in one of our product. We had returns from our customer stating unit did not power and upon investigation, it was figured out that output (pin 3) was shorted to ground (verified by measuring the resistance between pin 2 and 3). 

C8 was taken off the board and was found good i.e.not shorted.  

Recommended operating voltage for the product is 9-32VDC. I tried applying 24VAC to the unit for about 30 minutes to see if it could damage the IC, but it did not damage the IC. 

Beside ESD, what could be the other sources of damage of IC?

We get units back from our customer frequently with the same issue. So, what are the things/information I should look or request for further investigation?

 

  • TI__Genius 13850 points
    Hi Sanjib,

    I'm sorry to hear about customer returns. LM2936 is an quite old product but very reliable.

    If output is shorted to ground ESD is one possible reason. Of course there might be something else but hard to figure out without further failure analysis.

    Can you specify operating conditions for this circuit? Input, Output voltages and load current. Also operating temperature information would be beneficial.
    Have you disassembled broken LM2936 from a board and measured is short still present on the board? Or assembled new LM2936 ic for the broken one and see will it cure short situation?

    Best regards,
    Jari Niemelä
  • in reply to Jari Niemela13
    Prodigy 20 points

    Hi Jari,

    Thank you for your prompt reply.

    I will get the information you requested and will see if I can still see shorts on board after removing LM2936.

    Thank you

    Kind regards

    Sanjib