" EMC filter design criteria in SMPS"

Discussion in 'The Projects Forum' started by mishra87, Apr 29, 2016.

  1. mishra87

    Thread Starter Member

    Jan 17, 2016
    170
    2
    Can any body guide me what should be key criteria for design EMC filter " in below key terms-

    1. Which standard to be followed.
    2. How to calculate Common/differential mode capacitor.
    3. How to calculate x/y capacitor.
    4. how to calculate source impedance.
    5. what db of attenuation needed.

    Thanks in Advance !!!
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    I'm not sure there is a standard. Maybe you could show us your SMPS schematic, and where you plan to place the filter, and what you design goal is. I have no idea what a "Common/differential mode capacitor" is, and I have no idea what an "x/y capacitor: is. I've never had to add one to an SMPS; are you sure you will need one?
     
  3. RamaD

    Active Member

    Dec 4, 2009
    254
    33
    The regulatory authority specifies the required standard to be complied with, depending upon your application and the target market.
    Common mode & differential mode filter components depends on the standard to be comlied with, and the level by which your SMPS exceeds the standards.
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    They may specify requirements, but they don't specify an implementation. Any implementation that meets the requirements is compliant.
     
    Last edited: Apr 30, 2016
    RamaD likes this.
  5. RamaD

    Active Member

    Dec 4, 2009
    254
    33
    We, non-native English speaking guys, lack that communication ability!
     
  6. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,132
    267
    You need to start with the problem first, then look for a solution.

    An SMPS might create more conducted emissions than a standard calls for, then you would devise a way to reduce those emissions.

    If the emissions are below the limit, no problem.

    Standards do not define the filter type, they define maximum emission levels.
     
    mishra87 likes this.
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