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TPS54540

Madhuri Akkenepalli
Expert 1215 points
Other Parts Discussed in Thread: TPS54540

The question is about using TPS54540 as a negative power supply.  Specifically the enable pin.  We will need to enable this after the main power supply comes up, so I need to hold this power supply disabled.  Do you know what the turn on voltage will be when we use this as a negative power supply?

Thanks,

Madhuri

  • 0
    TI__Mastermind 35165 points

    Hi Madhuri,

    The turn on voltage will work the same way with the enable divider as long as the negative output is 0V as the main power supply comes up. This works because the TPS54540 GND reference is still at the 0V system ground. When the negative output voltage gets into regulation the turn off voltage becomes very low due to the shift in the GND of the TPS54540. The only thing to make sure is that the upper resistor is large enough to limit the current into the EN pin to below 100µA.

    Also the following app note presents an idea on how to manage it.

    http://www.ti.com/lit/an/slva540/slva540.pdf

    For some alternative ways in managing the EN pin, check out the following app note in section 2.

    http://www.ti.com/lit/an/snva425a/snva425a.pdf

    Best Regards,
    Anthony