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Reduction Solution of LM3488 Switching Frequency

Jayden Park
Expert 1100 points
Other Parts Discussed in Thread: LM3488

Hi!

Our customer using LM3488 device and doing EMC(Conducted Emission) now.

Our customer did measure Conducted Emission. Test Result is Fail about switching frequency.

Our customer want solution that reduce 400khz switching frequency

 

First Solution : Switching frequency reduction of device itself

Second Solution : PCB Artwork method and BPF design of DC input line and so on 

Please recommend solution as soon as possible.

 

  • 0
    TI__Genius 16025 points

    Hi Jayden,

    For input filter design guidelines and tips, please refer to App note AN-2162

    http://www.ti.com/lit/an/snva489c/snva489c.pdf

    In particular please checkout page 6 of the App Note, section titles: "Damping Capacitor".

    Also an RC snubber across the catch diode will probably help.

    Thanks,

    Anston

  • 0 in reply to Anston Lobo
    Expert 1100 points

    Hi~ Anston

    Thank you for your answer.

    Our customer found solution to reduce switching noise.

    If see attached schematic, our customer did add C37(10nF) to FB line.

    When applying C37, Do not have a problem with the normal operation?

    Please reply as soon as possible

    LM3488 Schematic.doc