LM25066A: Backfeeding voltage to Series Pass FET

Christopher Arntzen

Part Number: LM25066A

Hello,

Referencing the "Typical Application Schematic" in the LM25066A datasheet:

I would like to know if applying voltage to the output (Vout) with no voltage on the input (Vin) will damage the LM25066A. Doing this would create a voltage drop across the parasitic body diode in the series pass FET, and this voltage would be applied from the OUT pin to the SENSE and VIN pins. There are no ratings in the datasheet regarding OUT to SENSE or OUT to VIN.

over 5 years ago

0 Rakesh over 5 years ago

TI__Guru* 95801 points

Hi,

This should not be a concern as long as there is "no-load" at the Vin side. Any load on the Vin side would stress the parasitic body diode of the pass FET. If it reverse voltage is expected in your system, please consider back-to-back FET configuration to block the voltage.

Make sure that applied voltage at the output pin is with in the Recommended Operating Conditions <17V.
Can you share more information on your system requirements.

Best Regards,
Rakesh

0 Christopher Arntzen over 5 years ago in reply to Rakesh

Intellectual 580 points

Hi,

This is a 5V application.

There is about a 150mA load on the input side when I back-feed, but this load stress is brief on the body diode since the Pass FET will turn on once Vin reaches 5V (as soon as the capacitance on the Vin side is charged).

I'm not worried about this stress on the MOSFET, but am really just concerned with the voltage from the OUT pin to the SENSE and VIN pins. I just don't want to damage the LM25066A IC.

Thanks,

Chris

0 Rakesh over 5 years ago in reply to Christopher Arntzen

TI__Guru* 95801 points

Hi Chris,

This is not a concern and will not lead to damage the device.

Best Regards,
Rakesh

0 Christopher Arntzen over 5 years ago in reply to Rakesh

Intellectual 580 points

Thank you!

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LM25066A: Backfeeding voltage to Series Pass FET