How to Specify an EMI Filter

Abstract

exist (M IL-F-15733e \ f i l t e r manufacturers ' c a ta lo g s , e t c . ) there is a con tinu ing common d e f ic iency o f know ledge of re levan t and suffic ien t items to b e included in formal f i l te r procurement sp ec if ica t io n s . A sp ec if ie r will often d rastica lly over o r under specify the f i l te r a c tu a l ly n e e d e d , o r may g ive conflic ting requirem ents. Some o f the param eters discussed herein may be p re-im posed upon the f i l te r sp ec if ie r by a prime purchaser . This paper is devoted to assisting in cases ■ in which the immediate f i l te r spec if ie r has a major d eg ree of control o ver the process of g enera ting the f i l te r sp e c if ic a t io n . M ajor topics to be covered herein include desired in-system noise a tten u a t io n perform ance , d is tu rbance o f a system caused by f i l te r insertion , e le c tr ica l w ithstanding cap a b i l i ty o f a f i l te r , cost and volume im pact of unnecessary e le c tr ic a l re ­ quirem ents , env ironm en ta l /m echan ica l considera tions , and m echanical de s ig n . The approach used will be a discussion o f the important aspects o f f i l te r u sage , follow ed by a list of suggested spec if ica t ion p ra c t ice s , and a list o f p rac t ice s to a v o id .