具有高适应性的锂电池充电器IC的研究与设计

I摘要锂电池由于具有体积小、质量轻、寿命长、能量密度高等优点，在便携式电子设备中得到了广泛应用。锂电池充电器作为电源管理系统的重要组成部分，其能否为锂电池安全高效地充电，对锂电池的性能及应用来说至关重要。为了对锂电池安全、可靠、快速、高效地充电，本文结合锂电池的基本特性以及常用的充电方法，设计了一款针对单节锂电池的充电器IC。本文采用了以恒流恒压充电法为基础的三阶段法：第一阶段使用小电流对电池进行预处理，对出现过放电的电池进行修复和保护；第二阶段采用较大的恒定电流对电池充电，实现快速充电的目的；第三阶段采用恒压充电，确保电池充满。此充电器IC的昀大特点是其高适用性，可以使用各种不同的适配器和USB端口进行供电，尤其是当其结合电流限制适配器时，兼有线性式充电和脉冲式充电的优点，使充电效率大大提高。此外，本设计增加了芯片温度控制、电池温度检测与保护、电源状态检测和充电定时等功能等，实现了对充电过程的智能控制。本文采用0.5µmCMOSN阱工艺，降低了成本。通过HSPICE仿真可知，在各种工艺角，-40℃~125℃的温度范围和4.3V~6.5V的电源电压输入范围内，电池昀终充电电压达到4.1V±0.56％。充电器IC结合限定电流为0.5A的电流限制适配器进行恒流充电时，其充电效率高达96％以上。此IC还具有外部电路简单的特点，只需与外部少数电容、电阻配合使用，就可以完成充电功能。文中首先对锂电池的组成及化学原理进行了简单介绍，然后介绍锂电池的特性及常用的充电方法，接着说明充电器IC的整体结构和原理，昀后着重介绍内部具体电路的设计与实现，并给出了HSPICE仿真结果。关键词：锂离子电池，锂聚合物电池，充电器，恒流/恒压，电流限制适配器IIABSTRACTBecauseofsmallsize,lightweight,longlifeandhighenergydensities,Li-ionandLi-polymerbatteryhavebecomeincreasinglypopularinportableelectronicdevices.Chargerisanimportantcomponentinthebatterypowermanagementsystem.Inordertochargebatterysafely,reliably,fastandefficiently,basedontheLi-ionandLi-polymerbattery’scharacterandgeneralchargingmethod,achargerICforsingleLi-ionorLi-polymerbatteryisdesigned.ThechargingmodebasedontheCC/CVhasbeenadopted,inwhichtheprocesshasbeendividedintothreephases.Atthefirstphase,thebatteryispre-chargedwithatricklecurrenttorepairandprotecttheover-dischargedbattery;atthesecondaryphase,thebatterywillbechargedbyalargeconstantcurrenttoallowthefastcharging;atthelastphase,theconstantvoltagechargingisadoptedtoguaranteethebatteryfullycharged.TheparticularcharacteristicofthisICishighapplicability,becauseitspowersupplycanusedifferentadaptersorUSBports,especiallywhenusingthecurrent-limitedadapter,itintegratestheadvantagesoflinearchargingmodeandpulsechargingmode,whichimproveschargingefficiency.Besides,themodulessuchasthechiptemperaturecontrol,batterytemperaturedetectionandprotection,powerstatusdetectionandchargetimingarealsoaddedtothesystemtoallowtheintelligentcontrolofthechargingprocess.Theprocessof0.5µmCMOSwithNwellhasbeenapplied,whichreducesthecost.ThroughHSPICEsimulation,battery’sfinalfloatvoltagereaches4.1V±0.56%atdifferentprocesscorners,thetemperaturebetween-40℃and125℃,andinputvoltagebetween4.3Vand6.5V.Thechargingefficiencyisupto96%inconstantcurrentchargingphasewhentheICissuppliedbyacurrent-limitedadapterwhoselimitedcurrentis0.5A.ThisICsimplifiestheoutsidecircuitsothatitcanaccomplishallthechargingfunctionsonlyatthecooperationoffewadditionalcapacitancesandresistances.Inthispaper,thecompositionandchemicalprincipleoftheLi-ionandLi-polymerIIIbatteryarefirstlypresented,whicharefollowedbytheircharacteristicandcommonchargingapproachesintroduction.Andthen,thewholestructureandprincipleofthischagerisilluminated.Atlast,thedesignandrealizationofactualcircuitsareemphasized,theHSPICEsimulationresultsareprovidedaswell.Keywords:Li-ionbattery,Li-polymerbattery,batterycharger,CC/CV,currentlimitedadapterIV目录第一章绪论.........................................................1第二章锂电池特性及充电方法.........................................32.1锂电池的工作原理...............................................32.2锂电池特性.....................................................52.3锂电池对充电器的要求...........................................62.4锂电池充电方法.................................................7第三章锂电池充电器IC的系统分析与设计..............................113.1锂电池充电器IC系统的主要功能与特点...........................113.2锂电池充电器IC系统电路的设计.................................14第四章锂电池充电器IC内部电路的设计与实现..........................184.1带有欠压闭锁功能的基准电压源的设计与实现......................184.1.1基准电压的设计考虑........................................184.1.2带隙基准的原理............................................194.1.3欠压闭锁电路的设计与实现..................................204.1.42.8V基准电压的设计与实现.................................244.1.5可精确微调的基准电压源....................................284.2精确可调的基准电流源的设计与实现..............................324.2.1基准电流源结构的选择......................................324.2.2基准电流源电路的设计与实现................................344.3充电电流编程模块的设计与实现.................................364.3.1充电电流IREF的设定.......................................374.3.2终止充电电流IMIN的设置...................................404.4恒流充电的设计与实现..........................................424.5恒压充电的设计与实现..........................................484.6温度控制电路的设计与实现......................................52V4.6.1电池温度控制电路的设计与实现..............................524.6.2芯片温度控制电路的设计与实现..............................544.7定时电路的设计与实现..........................................574.7.1振荡器的设计与实现........................................574.7.2计数器的设计与实现........................................614.8其它电路的设计与实现..........................................654.8.1启动模块的设计............................................654.8.2电流采样电路的设计........................................664.9整体电路的仿真与验证..........................................674.9.1锂电池充电过程的仿真......................................674.9.2锂电池昀终充电电压的仿真..................................694.9.3锂电池充电电流的仿真......................................714.9.4漏电流的仿真..............................................724.9.5性能参数表..........................