适配器的热设计

《适配器的热设计》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、ThermalManagementDesignsforNaturalConvectionCooledLowProfileAdaptor1412mmSlimAdaptor,DesignApproachWhitePaperRev:1.0012-Mar-2003BackgroundThisisareportabouttheexperiencegainedfromthethermalmanagementdesignofaslim(12mmthickness)AC/DCadaptorusedinnotebookcomputerorportabledevices.Itiswellkn

2、ownthattheheatdissipationcapacityofanobjectisgovernedbyitssurfacearea.Packagemanufacturers(e.g.HoffmanSpecifier’sguide1995~1996P594)providespecifiedchartcurveforselectedmaterialsasshownbelow;byplottingthetemperatureriseagainstthepowerdissipationperunitarea.Thisprovidesanideaabouttheaverag

3、etemperatureriseofacertainshape.Howeveritdoesnotshowtemperaturedistributioninsidetheshapeandthereforecannotbeusedasatoolforidentifyingpossiblereliabilityissues.Thegraphicalmethodalsodoesn'tworkverywellforgeometrieswithextremeaspectratio.1412mmSlimAdaptor,DesignApproachWhitePaperRev:1.0012

4、-Mar-2003AgeneraldescriptionoftherequirementsInthisdesigntheenclosureisaboxmeasures50x80x12mm.Theboxismouldedfromplasticmaterialforsafetyreason.Copperplatesarelocatedattheinnersurfaceoftheboxthat"spreads"theheatgeneratedinternallyandequalizethetemperaturegradientalongtheinnersurfaceoftheb

5、ox.Themetalplatesalsodoublesaselectricalshieldforminimizingelectromagneticradiation.Electroniccomponentsaremountedona1mmFR-4glassepoxydoublesidedprintedcircuitboard.Theheatgeneratingcomponentsaresummarizedasfollows:-InputEMIfilter.-Inputrectifier.-Mainprimarypowerswitch.-Primarysnubber.-P

6、rimarycontrolcircuits.-Powertransformer.-SecondaryRectifier.-Secondarysnubber.-Secondarycontrolcircuit.-Outputcapacitors.ThesimulationmodelThermalsimulationisusedtoinvestigatetheairflowpatternwhentheenclosureissittinginahorizontalorientation.Fig.AandBarethe2dimensionalcrosssectionalviewsa

7、longthecentreline.Fig.AisalongthelongersideandFig.Bisalonetheshorterside.Theenclosurerestsonitslargestfaceandspaced1mmapartfromaflatsurface.Itcanbeseeairentersfromtheside,graduallyheatedupbythesurfaceoftheenclosure,andthenriseverticallyataregionroughlyatthecentreoft