[SOLVED] How to meet EMI & EMC standards?

[amayilsamy]

How meet EMI & EMC standards in product design.

For example In op amp circuits & transistor circuits

 

[schmitt trigger]

You must first study and become very familiar with the appropriate standards one requires to meet.

I'm Sorry about providing such generic reply, but EMI is a specialty that requires significant amount of expertise and knowledge.

There are cookbook recipes -for instance- power supplies and video signals, but nevertheless one must still tailor those recipes to the own circuit, and again, to the particular standard one has to meet.

So, first things first....You have to procure the appropriate standard published by the regulatory agency you'll be submitting your samples to. They can be ordered online.

 

[amayilsamy]

Thanks for your earliest reply.

I have one more doubt . How to design circuit to avoid Lighting effect in analog designs.

Any example designs or samples.

Because I'm New in these designs.

 

[Gorgon]

Re: How to meet EMI & EMC standards?

First of all you need to understand how your circuit is working and the the frequencies you need.
Then design it from inside out thinking of removing as much you can of any noise generated from your circuit.
A rule of thumb is that if your circuit don't emit, it will be less susceptible to inbound noise also.
Then you need to add the necessary high voltage/ frequency protection on all in- and outgoing signals.

One of the most critical 'components' are the layout of the PCB, removing any signal loops that can be an antenna for unwanted signals in and out of the circuit.

After your first EMC tests fails, you need to do another round of the above points, and try again.

This goes on until you hopefully get your approvals.

Good luck!

- - - Updated - - -

I have one more doubt . How to design circuit to avoid Lighting effect in analog designs.

Because I'm New in these designs.

You'll never make electronics that can take a direct hit from lightening.
Part of the EMC tests, at least in Europe, is a simulated effect of the lightenig to a degree.

To further help you survive the lightening, you add surge arrestors and different levels of overvoltage protection, normally 3 levels or more.

 

[amayilsamy]

What are the changes make these effect in op amp?

 

[schmitt trigger]

There is an app note from Littelfuse which describes all the pros and cons of the different protective devices.

In general, one requires at least 2 layers of protection. But the best approach is to shield first, protect afterwards.