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LM2674: Question about output noise.

David Kim2
Genius 3305 points
Part Number: LM2674

Hi

My customer asked questions about LM2674MX-3.3

LM2674MX-3.3 is used for products in production.
When 10,000 units are produced, two to three defects occur.
Only defective products are being repaired because the cause has not been found.
I'm inquiring because it's an intermittent phenomenon, so I think it's a design mistake.
The defective phenomenon generates noise at the output voltage.
SWAP test A-B-A also reproduces the fault.
Do you know what causes noise in the output voltage?

Thanks

  • 0
    TI__Guru 73235 points

    Hello

    Please provide a 'scope image of the suspect wave form on the SW node.

    Also, please provide a photograph of the top of the suspect unit and a photograph of

    the label on the reel of parts.

    From you schematic, you will need a 22uF tantalum or 100uF aluminium electrolytic on the input of the regulator

    in addition to the 100nF.  What is the size of your inductor ??

    Thanks

  • 0
    TI__Mastermind 31315 points

    Hi,

    Since it's been more than two weeks on this thread with no response, I will mark this as closed. Please reopen if support is still needed. 

    -Richard