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Power Tip 69: A Simple Oversight Can Ruin EMI Performance

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D Vanditmars
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Adding primary filters
D Vanditmars   3/12/2014 5:24:05 PM
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I wonder how many designs had a primary filter added and subseqently passed EMI only because components had to be moved to make room for the filter...

Thinking_J
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good observations... but...
Thinking_J   3/12/2014 7:13:48 PM
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Looks like the second (improved) layout made space for additional magnetics (L100) .. but wasn't installed (instead a 100 ohm and a smt inductor/ ferrite bead was installed)

So the design is no longer the same size... (?) a compromise that many of us cannot obtain when faced with these problems...that helped get that 3x spacing improvement.

 

 

Sheetal.Pandey
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Re: good observations... but...
Sheetal.Pandey   3/13/2014 11:47:56 AM
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Design review for EMI is a good to step to have in these complex designs. Yes the PCB layout makes lot of difference. Thanks to advancement in EDA tools, you can do a trial run on the layout before releasing the gerbers for PCB manufacturing.

GBrandly
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Re: Adding primary filters
GBrandly   6/26/2014 2:51:47 PM
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@dvandit: That was exactly the first thought that came to my mine when I read this. In this case I'd say the ends could well justify the means.  :)

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