SMPS with EMI Filter

[vinodquilon]

I am trying to build one SMPS with EMI Filter.
Can anybody give me the design equations and design criterion s of the filter ?

 

[Ubergeek63]

emi comes from a number of sources. EMI modes are conducted and radiated. Conducted goes out through the power line and radiated goes out as RF does through antennas.

keeping the switcher frequency "low" and modulated reduces emi as does controlling rise and fall times of both voltage and current.

Frankly you have given very little to go on as to your application and "design equations" are available all over the web as well as in basic electronics courses as RLC filters

 

[crutschow]

If you need a high degree of EMI suppression, then mount the SMPS in a sealed metal box with commercial feed-through EMI filters on all inputs and outputs to the box. The filter data sheets will show suppression versus frequency. You may also need common-mode filters on the input and output to minimize conducted EMI ground current.