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LM2596

Mike Thornhill
Intellectual 795 points
Other Parts Discussed in Thread: LM2596

All,

We have the LM2596 , 12V, fixed output on our board.

LM2596SX-12/NOPB


The input to the switcher is about 24V and I was expecting to see 12V on the output. Instead I am seeing 24V.

When I reexamined the datasheet there is a circuit guideline for fixed output and adjustable output versions.

Turns out we have the fixed output in the adjustable version of the circuit. Meaning there are some other components in the feedback sections. (cap, 2 resistors).

I am thinking I will just remove these components and just short the regulated output back to pin 4 (feedback) through he pads of the removed components.

I just wanted to get some feedback from the forum to be sure I am not missing something here.


Thank you.

-Mike

 

 

  • 0
    TI__Genius 15810 points

    Hello Mike,

    If you're using a fixed output LM2596SX-12, then the feedback resistors are internal to the part. Therefore if you have any external resistors, the design won't work well. If you remove those feedback resistors and short FB to output, then you should have a regulated 12V at the output. I hope this helps.

    Regards,
    Akshay