磁环、磁珠原理及选型指南.pdf

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1、applicationnotePhilipsMagneticProductsCableShieldingPhilipsComponentsCableShieldingContentsIntroduction3EMIsuppressionandcableshieldingwithferrites4Ferriteselection6Materialproperties7Ferritecoreanditsimpedancebehaviour11Ferritelocation12Impedanceconcept13Attenuationconcept16Productrang

2、e171PhilipsMagneticProductsOurrangeofferritecableshields2PhilipsMagneticProductsIntroductionElectromagneticinterferenceproblemscanariseanywhereConductivecouplingisthemostcommonwayansinceelectromagneticenergycanunpredictablycoupleintointerferencesignalistransmittedtoasystem.systems,produ

3、cingunwantedeffects.Whenstudyinganinterferenceproblem,veryoftenattentionisfocusedoncriticalcomponents,whilesystemElectromagneticinterferenceoccurswhenthreeelementscablesareoverlooked.cometogether:Acablecanpickupsomenoiseandbringittootherareas·asourceofinterferencetraversedbythecable.·ar

4、eceiveroftheinterference·apathoftransfer.Withtoday’sregulations(VDEinGermany,FCCinUSA,VCCIinJapan),allelectricandelectronicproducts,noAccordingtothissimplescheme,minimizingthematterhowtrivialtheyseemtobe,havetocomplywithelectromagneticinterferencecanbeattainedbyeliminatingcertainEMClimi

5、ts,bothforemissionandreception.oneofthethreeelements:·suppressingthesourceThereisaneedtosuppresscommonmodeEMInotonly·protectingthereceiveragainstnoiseoninternal,butalsoonexternalcablesofelectronic·reducingtheinterferencetransmission.equipment.Thisbrochureconcentratesononeoftheelements:P

6、HILIPSCOMPONENTSdevelopedanewrangeoftransmissionofinterferencecableshieldingproducts.TherearetubularcableshieldsforcoaxialcableandAnydevicewhichsuppressesnoisebetweenthesourceandrectangularcoresforflatribboncables.AlsosplittypesforthereceiveractsasanEMIshield.retrofitsolutionsareavailab

7、le.Interferencescanpropagateindifferentways:TheseEMIproductsprovideahighimpedanceleveloverawidefrequencyrange.·Byradiationasanelectromagneticwaveinfreespace.SuppressionthenrequiresshieldingwithconductiveFerritecableshieldsarecost-effective,astheysuppressanyorabsorbingmaterials.