Guidelines to make circuit capable of EMI/EMC

[sijukrishnan]

Could someone throw light on the points while designing circuit to manage EMC/EMI. It may not be possible to cover the whole things in circuit design alone but still some guide lines could save an iteration of board development. The most important few things...

 

[leo_o2]

Add small capacitor like 10pF to filter high-frequency noise.

 

[lokesh88]

1 to 10uF is better...

 

[audiomik]

sijukrishnan

if you can post a diagram of your proposed circuit, then some advice can be given to reduce both immunity and radiation.
Mik

 

[leo_o2]

Agree with Mik. Some special techniques can be used for specific circuits and applications.
Megnetics beads and RC filter somewhere are examples.

 

[sijukrishnan]

Dear Mik, Leo, lemme clarify this, I was not referring to a particular circuit. I just enquired on the points which can be noted down as a reference before starting a new design. I don't have a circuit to share with.
Thanks

 

[audiomik]

sijukrishnan

you may find this link useful as a starting point:
eEngineer -- EMI/EMC Printed Circuit Board (PCB) Tips

Mik

 

[leo_o2]

Please also place big area ground plane.

 

[poorchava]

Also, remember to keep tracks as short as possible (unless you are using controlled impedance tracks) and as straight as possible without breaking 90/45 angle rule. Also, 100 nF ceramic + 10 uF tantalum electrolitic capacitors in large quantities. Especially the ceramic ones, stuff them wherever u can, since they cost next to nothing. As it was mentioned by leo_o2 fill all remaining space with ground planes. If your board is 2 layer then remember to place multiple vias just to connect ground planes in various places (like 1 via every 4mm). If your board has more than 2 layers use middle layers for power and ground. In this sint' critical in your application try to lower signal rising times by placing series resistor on signalling lines (like 100R or so).

There is a lot, lot more of that stuff.