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ON OFF control for LM2679S-ADJ

JOSE ANTONIO LLUCH
Prodigy 110 points

Other Parts Discussed in Thread: LM2678

Hello,


I am using LM2679S-ADJ for different voltage applications. So far I didn't need to control ON/OFF of this regulator. But now I will need.


I can see that there is no dedicated pin for this function. But I guess that may be SS (#7) pin can works in this sense if I pull down with a transistor.

Is this OK? I couldn't get this confirmation clearly from datasheet or evokits AN

And if yes, which current drawn can I estimate in order to choose proper transistor?

thanks

  • 0
    TI__Guru* 85755 points

    Pulling the SS pin to ground will probably stop the switching completely; but you will have to test that.

    Some parts will not go to zero duty cycle when the SS pin is pulled low, so there would be some

    residual output; test before you commit to a final design.

    The current in the SS pin is only a few uA, so any small FET such as the 2N7000 should work.

    The LM2678 is a 5A part with an enable pin; that may be a better choice for you.

    FD

  • 0 in reply to Frank De Stasi
    Prodigy 110 points

    Hello Frank,

    OK, now its clear, I understand. Better to use proper regulator. I will consider LM2678, thank you for your prompt reply

     

    regards

     

    Josep