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TPS54560: Pulling TPS54560 EN pin with its own output and a series diode

Ganapathi rao
Intellectual 320 points
Part Number: TPS54560

Hello,

I am using TPS54560 for 5V generation on my board and pulling its EN pin with its own output as shown below with a series diode. If diode is not present, this converter never turns on, hence used a diode.

And also i have many converters on same board for 15V, 24V, 19V etc.. generation on same board with TPS54560 and pulling EN pins of all these converters with 5V generated from above said converter. I hope this shall be OK.

Thanks & Regards

Ganapathi

  • 0
    TI__Mastermind 23845 points
    Hi,

    I am not sure how the 5V output is generated in the first place if the part did not turn on. I think this part has a internal current pull up for EN to turn on the part.

    Thanks
    -Arief
  • 0 in reply to Arief Hernadi
    Intellectual 320 points
    Hi Arief,

    This part TPS54560 has internal pull up by weak current source. As this is a weak current source, i am pulling up EN pin with a 5VDC. As i don't have any other low voltage power supply to pull up EN pin, i am pulling up EN pin of this power supply with its own output 5VDC.
    Consider if diode is not present, internal pull up sees a leakage path through feedback resistors to ground and converter never turns ON.Hence, i have put a diode in reverse bias direction so that internal current source cant see a leakage path to ground.
    When i provide input voltage, converts turns ON and 5V appears at its output and EN will be pulled up to 5VDC.

    I would like to know is it good design or any issues in long term operation?

    Thanks
    Ganapathi
  • 0 in reply to Ganapathi rao
    TI__Mastermind 23845 points

    Hi,

    I think in general is ok to do this. Keep in mind that there is a zener diode 5.8V in the EN pin of this device.

    Thanks

    -Arief