微电子专业英文翻译Word文档下载推荐.docx

微电子专业英文翻译Word文档下载推荐.docx

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Abstract

ThispaperpresentsembeddedprocessorbasedautomatictemperaturecontrolofVLSIchips,usingtemperaturesensorLM35andARMprocessorLPC2378.Duetotheveryhighpackingdensity,VLSIchipsgetheatedverysoonandifnotcooledproperly,theperformanceisverymuchaffected.Inthepresentwork,thesensorwhichiskeptverynearproximitytotheICwillsensethetemperatureandthespeedofthefanarrangedneartotheICiscontrolledbasedonthePWMsignalgeneratedbytheARMprocessor.Abuzzerisalsoprovidedwiththehardware,toindicateeitherthefailureofthefanoroverheatingoftheIC.TheentireprocessisachievedbydevelopingasuitableembeddedCprogram.

Keywords:

Temperaturesensor,ARMprocessor,VLSIchips,BrushlessDCmotor

1.Introduction

WiththephenomenaldevelopmentsinVLSItechnology,theambitiousICdesignersaretryingtoputmoretransistorsintosmallerpackages.So,theICsrunathigherspeedsandproducelargeamountofheatwhichcreatestheproblemofthermalmanagement.Forexample,nowadaystheCPUchipsarebecomingsmallerandsmallerwithalmostnoroomfortheheattoescape.Thetotalpowerdissipationlevelsnowresideontheorderof100Wwithapeakpowerdensityof400-500W/Cm2,andarestillsteadilyclimbing.

Asthechiptemperatureincreasesitsperformanceisverymuchdegradedbyparametersshift,decreaseinoperatingfrequenciesandout-ofspecificationoftimings.Sothehighspeedchipsmustbecooledtomaintaingoodperformanceforthelongestpossibleoperatingtimeandoverthewidestpossiblerangeofenvironmentalconditions.Themaximumallowabletemperatureforahighspeedchiptomeetitsparametricspecificationsdependsontheprocessandhowthechipisdesigned.

Amongthevariouscoolingtechniques,heatsinks,heatpipes,fansandclockthrottlingareusuallyemployed.Amongthesetechniques,fanscandramaticallyreducethetemperatureofahighspeedchip,buttheyalsogenerateagreatdealofacousticnoise.Thisnoisecanbereducedsignificantlybyvarying,thefansspeedbasedontemperaturei.e.thefancanturnslowlywhenthetemperatureislowandcanspeedupasthetemperatureincreases.Theotherprominentmethodisclockthrottlingi.e.reducingtheclockspeedtoreducepowerdissipation.Butitalsoreducesthesystemperformanceandthesystemsfunctionalityislost.So,theobjectiveofthepresentworkis,todesignahardwaresystemconsistingofabrushlessDCmotorfanwhosespeediscontrolledbasedonthetemperatureofthechip,sensedbythesensorLM35.TheLM35seriesareprecisionintegrated-circuittemperaturesensors,whoseoutputvoltageislinearlyproportionaltotheCelsius（Centigrade）temperature.TheLM35thushasanadvantageoverlineartemperaturesensorscalibratedinKelvin,astheuserisnotrequiredtosubtractalargeconstantvoltagefromitsoutputtoobtainconvenientCentigradescaling.TheLM35doesnotrequireanyexternalcalibrationortrimmingtoprovidetypicalaccuraciesof±

1⁄4°

Catroomtemperatureand±

3⁄4°

Coverafull−55to+150°

Ctemperaturerange.Lowcostisassuredbytrimmingandcalibrationatthewaferlevel.TheLM35’slowoutputimpedance,linearoutput,andpreciseinherentcalibrationmakeinterfacingtoreadoutorcontrolcircuitryespeciallyeasy.Itcanbeusedwithsinglepowersupplies,orwithplusandminussupplies.Asitdrawsonly60μAfromitssupply,ithasverylowselfheating,lessthan0.1°

Cinstillair.TheLM35isratedtooperateovera−55°

to+150°

Ctemperaturerange,whiletheLM35Cisratedfora−40°

to+110°

Crange（−10°

withimprovedaccuracy）.TheLM35seriesisavailablepackagedinhermeticTO-46transistorpackages,whiletheLM35C,LM35CA,andLM35DarealsoavailableintheplasticTO-92transistorpackage.TheLM35Disalsoavailableinan8-leadsurfacemountsmalloutlinepackageandaplasticTO-220package.TomonitorthevoltageattheterminalsoftheDCmotorfan,thePWMsignalisgeneratedbytheARM7TDMIprocessor.ThisPWMsignalischangedinaccordancetotheoutputoftheLM35temperaturesensor.Sotheimportantcomponentofthisentireprojectisthetemperaturesensor.

2.Description

InARMprocessorbasedautomatictemperaturecontrolsystem,theoutputofthetemperaturesensorisfedtotheonchipADCandtheoutputoftheADCisgiventotheL293DdriverICwhichinturnisfedtoDCmotorfanasshownintheblockdiagraminFig.1.AgraphicLCD（128x64pixels）isinterfacedtotheARMLPC2378processortodisplaythetemperatureoftheICandthespeedofthefan.Abuzzerisalsoconnectedtotheprocessorwhichgivesanindication,incaseofthefailureofthefanoroverheatingofthechipbeyondsomelevel.TheentirecircuitdiagramisshowninFig.2.

Fig.1.Blockdiagram.