facing problem in pcb grounding

[raksha singh]

hii
i am working on a project that is power supply ......i am i have done with the placement ,but i am confused in grounding ..can any one help me with this...
specification for smps pcb board is-
universal input ,output is 80v,1.25A and board size is 60mm X 180mm.
there is an isolation in primary side and secondary side...
please help me as soon as posssible...

 

[sivamani]

I Think you shroud take care of Creep age and clearance guidelines.Please browse it web you will get guidelines for this.

 

[marce]

Initialy some notes on SMPS EMC design, very very important. With regard to grounding could you eleborate on your concerns... The main thing is to work out the switching loops and contain these so they do not effect the rest of the circuit whilst still keeping a near as contigous ground as possible.

Switcher EMC design

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Some interesting articles regarding EMC and switch mode design which may be of interest to any one designing and laying out any form switching circuit be it an SMPS or Class D amp. As these circuits can be one of the main causes of noise in circuits following good EMC and layout guidelines is critical.
Anyway hope they are of interest and if anyone has any additions I would be grateful.

Excellent articles on EMC issues of SMPS design near the back.
http://www.compliance-club.com/pdf/Issue93.pdf
http://www.compliance-club.com/pdf/Issue94.pdf
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http://www.onsemi.com/pub_link/Collateral/AND8301-D.PDF

An eclectic mix of app notes from my collection.
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http://www.fairchildsemi.com/an/AN/AN-6203.pdf
http://www.fairchildsemi.com/an/AN/AN-6858.pdf
http://www.fairchildsemi.com/an/AN/AN-42036.pdf
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http://www.compliance-club.com/pdf/Issue93.pdf
http://www.compliance-club.com/pdf/Issue94.pdf

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http://www.onsemi.com/pub_link/Collateral/AND8301-D.PDF

For industrial units calculate clearance and creepage with a pollution level III, for domestic polution level II, if in any doubt use level III worse case, generaly this is 4mm clearance 8mm creepage.