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TPS74801 / Leak path from SS pin to GND due to condensation water

S.Satoshi
Guru 21675 points
Other Parts Discussed in Thread: TINA-TI

Hi,

My customer need to consider to be created leak path from SS pin to GND due to condensation water. I tried to simulate to create leak path by using TINA-TI then VOUT was dropped because VSS was dropped due to leakage. Then I tried to add external pull up to add Iss. As the result, VSS was not dropped and VOUT could keep to regulate.

Do you have any concern to add pull up between VIN and SS pin? I understand that the soft start time will be faster by adding external Iss.

TPS74801 SS pin leak path.pdf

Best Regards,

Sonoki / Japan Disty

  • 0
    TI__Guru 55940 points
    Sonoki-san,

    We have not designed the device with this type of application in mind and have not characterized the device under this type of scenario. The initial concern would be that you do not properly discharge the capacitor. This would affect subsequent startups.

    Please note that a leakage path due to water would not only affect the soft-start circuitry. It would also affect the FB pin and potentially bias the output voltage higher or lower than desired. A more robust solution would be to find a way to prevent the condensation.

    Very Respectfully,
    Ryan