Noise in smps

Discussion in 'The Projects Forum' started by tpseh9985, Oct 25, 2009.

  1. tpseh9985

    Thread Starter New Member

    Aug 31, 2009
    4
    0
    Hi,

    I am using SMPS in my design to reduce temperature raising rate. The drawback is that noise generated is quite high, about 10%. So, I am finding a way to reduce the noise. May anyone suggest a way to reduce the noise? Some information is that my SMPS is at 100kHZ. Can I assume that the noise is at 100kHZ? I try using bandstop filter at 100kHZ. But it does not work. Please help me on this. Thank you.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Use a low-pass filter.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Look up Pi filter on Wikipedia. They are simple and effective.
     
  4. Thav

    Member

    Oct 13, 2009
    82
    0
    If it's a hard switching power supply (most likely) then the noise generated by it will have frequency content up to 1MHz at least. I recently did a design at 400kHz that had radiated noise up to 30MHz!

    SgtWookie and Bill are putting you on the right track.
     
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    Do you mean EMI noise as in electrical interference?

    No, the EMI generated will have significant energy content out to hundreds of Mega Hertz.

    Containing EMI in a switcher is not a simple topic, it has many facets. It requires laying the PS out optimally, using shielding correctly, and L-C filters on lines entering and leaving the hot areas so EMI is not conducted out.
     
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