基于单片机的智能手机充电器的设计英文版doc 11页.docx

基于单片机的智能手机充电器的设计英文版doc 11页.docx

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基于单片机的智能手机充电器的设计英文版doc11页

基于单片机的智能手机充电器的设计（英文版）（doc11页）

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conventionallinearchargers,oneofthegreatadvantagesofusingswitchingchargerssolutionisthecapabilitytoboostthechargecurrentfromwhatsuppliedbythesource.ThisisespeciallyimportantwhenpoweringoffofaUSBportwherethecurrentavailablemightbelimitedtolessthan500mA.Higherchargecurrentsequatetoshorterchargecyclesthussatisfyingcustomerexpectations.

Therearetwokindsofbatterychargersusedinmosthandheldsnow–linearchargersandswitchingdevices.Linearchargershavealongerhistory.Theyhavetypicallyprovidedarelativelyefficient,simplewaytochargeportabledevices,creatingminimalnoisewithoutmanyexternalcomponents.Butasportabledevicesbecomemorecomplexandaddlayersofnewfeatures,theyneedhigherbatterycapacity.Linearchargerspresentliabilitiesduetopowerdissipation,whichbecomeclearifauserwantstochargeadevicewhileusingatthesametime.Theheatgeneratedwhilesimultaneouslyusingandchargingcandamagethesystemorbattery.Notagoodoutcome.

Thealternativeisaswitchingdevice,orswitchmodebatterychargerIC,thatcandeliverhighercurrentlevelstoabatterywhilerequiringaslittlepoweraspossible.Historically,therehavebeensomenoiseissueswiththesekindsofICs.Inaddition,someearlygenerationsofswitchmodedeviceshaverequiredseveralexternalcomponents.

However,thebenefitsoftheswitchedmodebatterytopologyareclear.Theyincludehigherefficiencyandlowerpowerdissipation,alongwithfastchargingcycles.Thesedevicesalsoarecapableofchargingfromhigherinputvoltages,whichallowstheuseoflowercostunregulatedadapters.Theycanincreasethechargingcurrentfromcurrentrestrictedsources.

Thenoisefromswitchingchargersusuallycomesduringlightloadoperation,particularlyduringpreconditioning.Asitdecreases,manyswitchingchargersmoveintoanoperationknownaspulseskipping.Inpulseskipping,thePWMfrequencychangesasynchronously.TherehavebeenbatterychargerICsdevelopedthatsupplyhighchargecurrentwithminimalthermalimpacttothesystemusingaswitchingcharger,thenswitchintoalinearchargerduringlowcurrentchargingmodestominimizenoise.ThistypeofPWMswitchmodechargerwithalinearmodehasbeenagooddevelopment,providinghighefficiencyatthefullconstantcurrent（fastcharge）rate.Theswitchingchargercontrolslargeconstantcurrentcharge（upto2A）withaPWMswitchingregulator.Itautomaticallymovestolinearmodewhilethebatteryispreconditioningandneartheendofconstantvoltagetaperchargemode,whichlowersthenoisewhiletheswitchmodespeedsupcharging.Oncethechargecurrentleveldipsbelow300mA,thelinearmodekicksincompletelyandnoisegeneratedbytheswitchingconverteriseliminated.

Butnowtherearefurtheradvances.Forexample,anidealsolutionfornewhandheldsisacompletechargerforsinglecellLi+/Polymerbatterieswithupto1Achargecurrentandadvancedindicationcapabilitiesforfullchargesystemmonitoring.USBCompliant100mA/500mAchargecurrentsettingsarebeneficialasareprogrammablepre-chargeandfastcharge.Manyproductsalsoincludebatterytemperaturemonitoring,whichensuressafecharging.

CompaniessuchasIntersilareleadingthedevelopmenteffortfornewgenerationsofchargerICs.Thesefullyintegratedsolutionsservecompactapplicationsandprovidechargecontrollersforhigherpowerapplications.Chargevoltageaccuracyisnowat0.5percent,animprovementoverjustafewyearsago,whenanaccuracyratingof1percentwasconsideredgood.Switchingfrequenciesareupto3MHzandnewswitchingchargersnowprovideupto2Achargecurrent,withonerecentexamplebeingtheISL9220,whichissuitableforboth1and2cellsLiIonapplications.

Inaddition,newdesignsrestrictleakage--thereisnolessthan0.5uAtypicalleakagecurrentoffthebatterywhennoinputpowerisattached.Theseimprovementsalsohavebecomeavailableinsmallerandsmallerpackages,suchas4x4mmQFNsor2x2mmCSPs,whichsaverealestateinspace-constrainedhandheldequipment.

ThelatestbatterychargerICsalsoareabletomonitortheinputvoltage,thebatteryvoltage,andthechargecurrent.Whenanyofthethreeparametersexceedsspecificlimits,theICturnsoffaninternalN-channelMOSFETtoremovethepowerfromthechargingsystemtothebattery.Thiskindofflexibleefficiencyisanotheroftheimprovementsnowavailableintheseimportantdevices,whicharevitaltothecontinuinggrowthandfeaturesetexpansionofmobile,handheldproducts.

【作者】Marino,Giampaolo;Schmitz,Tamara

【刊名】ElectronicComponentNews

【出版日期】2010

【卷号】Vol.54

【期号】No.1

【页码】16

DESIGNANDIMPLEMENTATIONOFAMICROCOMPUTER8051SYSTEMPOWEREDBYDUALBATTERIESCHARGEDBYSOLARCELLS

Abstract

Single-chipmicrocomputersystemsarebecomingincreasinglypopularincurrentcontrolandinformationapplications.However,duetotheirbatteryenergylimitations,thesesystemshaveaveryrestrictedoperationtimeorrechargecycleifasinglerechargeablebatterysuppliestheirpower.Weproposeadesignandimplementationforthesoftwareandhardwareofamicrocomputer8051systempoweredbyadualrechargeablebatterythatischargedbysolarcells.Fromafeasibilityanalysisofthequeueingmodelforthestochasticcharginganddischargingprocessofthedualbatterysystem,duetotherandomcharacteristicsofweatherconditionsandusers'operationalbehavior,weconfirmthattheaverageoperationtimeforthismodelcanbemuchlongerthanthatofasinglerechargeablebatterypowersupply.Theexperimentalresultsofourdesignalsoshowapproximatelythesameresultsasourmodel.Withatwo-thirdsutilizationratio,wecanobtainanaverageoperationtimefourtimesaslongintheoreticalresults,andthreeandhalftimesaslonginexperimentalresultsthanwithasinglerechargeablebatterypowersupply.Inaddition,thetechnologytrendshowsthatthepowerconsumptionrateforatypicalmicrocomputersystemisdecreasingandthepowergenerationefficiencyfortypicalsolarcellsisincreasing.Hence,solarcellsasthepowerchargingsourcesforamicrocomputer8051systemsuppliedbyadualrechargeablebatterycanbefeasibleinthenearfuture.

Overthepastfewyears,microcomputersystemdesignresearchershavebeenworkingwithdifferentlevelsoflow-powertechnology.Intermsofsystem,circuits,anddevicepowersaving,theresultsshowthateveryyearfrom1992to1997theaveragepowerconsumptionofamicrocomputercomputerdecreasedmorethan20%,andfrom1998to2001itdecreasedby10%.Reducingpowerconsumptionisimportantbecauseofitspotentialtoextendtherechargeperiodofportableinformationapplications.Thelongerthebatteryoperationtimebeforearechargeisneeded,themoreconvenientitisformobileuserstooperateaportablemicrocomputersystem.

Eventually,thepowerconsumptionofasingle-chipmicrocomputersystemwillbesmallenoughtobesuppliedorrechargedbyotherpowersources.Oneoftheproposedpowersourcesismechanicalvibration.Amongothers,wepreviouslyproposedsolarcellsthatcanbeusedaspowersupplysources.Althoughcurrentmc-Sisolarcellpowergenerationefficiencyisnothighenough,theirefficiencyincreasedfrom14.2%to16.8%from1990to1997.Thisimprovementcanreducethegapbetweenthecharginganddischargingrateofthepowersupplyofamicrocomputersystem,sotheprobabilityofpowerexhaustionwithinacertainoperationaltimeisreducedeachyear.

Toprolongthebatteryoperationtimebeforerecharging,inthisarticlewepresentthesoftwareandhardwaremoduleforasingle-chipmicrocomputer8051systemwithadualbatterychargedbysolarcells.Basedonitsdesignandimplementation,thisworkalsopresentstheestimationforpowerexhaustionprobabilityandtheexperimentalmeasurementforoperationtimethatdependsonthepowergenerationefficiencyofsolarcellsandthepowerconsumptionrateofamicrocomputer.Inaddition,duetotheoverlappingofthechargingandthedischargingperiod,iftheratiobetweenthecharginganddischargingrateistwothirds,thentheoperationtimecanpotentiallybeprolongedfourtimesincomparisonwithasinglerechargeablebattery.

Therestofthisisorganizedasfollows.InSection2,thetechnologytrendswithrespecttothepowerconsumptionofamicrocomputerandthepowergenerationefficiencyofsolarcellsarediscussed.InSection3,thequeueingmodelforthestochasticcharginganddischargingbehaviorforthedualrechargeablebatteryinasingle-chipmicrocomputersystemispresented.Inaddition,thefeasibilityestimationforthedualrechargeablebatteryinasinglechipmicrocomputersystemisgiven.InSections4and5,thedesignandimplementationofthesoftwareandhardwaremodulesforthissystemareprovided.InSection6,theexperimentalresultsofthissystemaregiven.Thelastsectionpresentsconclusions.

7.Conclusions

Wehavepresentedthedesignandimplementationofamicrocomputer8051systempoweredbydualbatterieschargedbysolarcells.Thehardwarecomponentsusedareverycommonandareoflowcost.Thecontrolprogramdesignedusesacommonvarietyofassemblylanguage.Theexperimentalsystemhasshownaverystable