A_PCB_design_approach_for_best_EMC

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1、APCBdesignapproachforbestEMCTimJarvisBScCEngMIEEMIEEERadio&EMCSpecialistAPCBdesignapproachforbestEMC22/06/2004IntroductionnPresentationHistorynTimJarvisBScCEngMIEEMIEEEnApproval1999nRF/AnalogueEngineerConferencenSincegraduatingin1983nBestpracticeincircuitnOffshoreandNavalSonarb

2、oarddesignnDSP/EmbeddednIEENewIssuesinnDetour1987to1997DesignApril2004nTelecommunicationsindustrynPracticalPowerPlanesforEMCnRF&EMCsince1991nAutomotiveEMC2004nFoundedRadioCADin2000followingnPracticalPowerPlanesredundancy.forEMC.Slide2APCBdesignapproachforbestEMC22/06/2004Design

3、ApproachesnIgnoreEMCrequirementsnAd-hoc(random)designrulesnStandarddesignrulesfirstprinciplessystematicapproachSlide3APCBdesignapproachforbestEMC22/06/2004Pre-PCBQuestionsnWhatisourEMCtarget?nEmissionsnImmunitynESD,etc.nMarketaccessnProductsafetynOtherdirectivesnConflictingstan

4、dardsSlide4APCBdesignapproachforbestEMC22/06/2004Pre-PCBQuestions(continued)nWhatareourproductconstraints?nAnticipatedvolumesnHighvolume=spenttimeengineeringforlowestcost=minimumPCBlayers(2-layers)nLowvolume=minimiseengineeringtime=morePCBlayers,plentyofcomponentoptions.nCompon

5、enttechnologiesnFastsemiconductors(fasterthanweneed?)nCheappassives(spend£stosavepence?)Slide5APCBdesignapproachforbestEMC22/06/2004Pre-PCBQuestions(continued)nSegregationattheschematiclevelnWhatareoursystemblocks?nWhichblocksarenoisy?nWhichblocksaresensitive?nWhataboutportsand

6、connectors?nImport/exportEMI/ESDnInteractwithshield/enclosureboundarynBuyorbuildEMIfilters?Slide6APCBdesignapproachforbestEMC22/06/2004PCBStep1-PlacementnRULE1-Neverusetheauto-placerandalwayssegregatesub-systemsSensitivecircuitryPSTNsocketwellawayfromcablesandnoisydigitalcircui

7、try.InsensitiveCircuitry,inthiscasewithoutagroundplane.HandsetSocketInthisreal-worldexamplethenoisydigitalcircuitrywasplacedonanotherPCB.Slide7APCBdesignapproachforbestEMC22/06/2004FilterPlacementnRULE2-Alwaysplacefiltersonsystem/sub-systemboundariesEXAMPLEThinkaboutµleakaround

8、¶Laytheinlinecomponentacrosstheboundarywithshuntcompon