Difference between EMI filter and low pass filter

[arr_baobao]

i had seen a lot of EMI circuitry a lot of them are kind of the same as typical low pass filter.
so my question here is is EMI filter have the same circuitry as low pass filter?
are they work the same way?

if not can someone tell me the different betweem the circuitry them and how EMI circuit should work.

thanks

 

[goldsmith]

Re: EMI filter circuitry

Dear arr_baobao
Hi
Most of EMI filters are kind of differential filters . and they won't allow unwanted harmonics , go through the power line .
Best Wishes
Goldsmith

 

[arr_baobao]

Re: EMI filter circuitry

differential filter? what's that. is that low pass filter?
that only allow low freq signal pass through them, bt attenuate high frequency signal like 2nd 3rd .... harmonics? am i correct?

 

[emontllo]

Re: EMI filter circuitry

EMI filters can be seen as "low pass filters" specially designed to block certain frequency ranges. In addition they are designed to manage certain current ranges, meet some efficiency target, withstand transient events such as surges or pulse bursts, or block high frequency noise both in common mode and differential mode.

So... yes an EMI filter is a kind of low pass filter. However not any low pass filter can be used as EMI filter.

 

[AMSA84]

Re: EMI filter circuitry

Taking the advantage of this post, I had this doubt for a long time but regarding the method to design it. How it is done?

Best regards.

 

[emontllo]

There several types of EMI filters (AC Line filters, DC supply filters, low power signal, etc.). Please specify which application are you targeting and we will be able to help you!

 

[AMSA84]

The AC Line filters. How can we design it?