【作者】 王磊；

【导师】 邢建力；

【作者基本信息】 厦门大学 ， 电路与系统， 2007， 硕士

【摘要】 随着便携式电子产品的高速发展以及可充电电池市场的不断增大,研究如何充分适应电池特性,最大可能延长电池寿命,并且符合电子设备充电单元小型化的发展趋势,具有较高效率、安全快速的充电器芯片,具有十分重要的意义。本文从锂电池化学特性与工作原理入手,通过对可充电电池特性认识以及常用充电方法的研究,分析了充电过程及充电方法对锂电池性能的影响,并在此基础上完成了一款锂离子电池线性充电器芯片的设计。该锂电池充电器芯片采用了恒流恒压(CC/CV)线性充电方式,能够提供高达1A的可编程充电电流,为充分保护电池,将充电过程细分为三个阶段:涓流预充电、恒流充电和恒压充电。先检测待充电电池电压,对过放电电池在充电初期采用涓流对电池进行激活处理;然后采用较大的恒定电流对电池充电,实现快速充电的目的;充电后期采用恒压浮充,确保电池充满。这种充电方式具有充电时间短,充电效率高的优点。芯片内部检测电路通过检测锂电池的电压和电流,确定锂电池应该进行的充电阶段。本文设计的充电器芯片面向单节锂电池,除了具有完善的充电算法外,提供了基于可设置时间和可设置电流的充电终止方案。芯片内部使用专门的带隙基准电压源以及基准电流源,高电源抑制以及出色的温度特性保证了浮充电压精度。由于对芯片整体电路的设计采用了内部MOSFET架构,无须使用外部检测电阻器或外部隔离二极管,因此基本充电器电路仅需要两个外部元件,简化了芯片应用,热调整功能可自动调节充电电流,以便在大功率工作或高环境温度条件下对芯片温度加以限制。对应于每一项技术或功能,文章介绍了各个电路模块的结构和工作原理。最后,文章基于0.5um的CMOS N阱工艺库对重点模块电路以及整体电路做了HSPICE仿真,验证了设计的可行性。更多还原

【Abstract】 As the development of portable apparatus and secondary built-in battery has been proliferating rapidly in recent years, it is significant and necessary to give a research on design of safe reliable, fast and high efficient charger which is suitable to battery characteristic, able to extend the battery life and in accord with miniaturization of charging unit.In this thesis, the chemic structure, performance and charging method of lithium-ion battery are studied. And different impacts on the performance of battery via different charging ways and process are analyzed in detail, based on which, an linear charger IC for Li-ion battery is designed. Using the constant current/constant voltage algorithm, the charger can deliver up to 1A of programmable charge current. The charging mode includes the three charging stages: the trickle charging, large constant current charging and constant voltage charging. The trickle charging uses small current at the initial of charging cycle to fix and protect the over-discharged battery; after which, the battery will be charged by large constant current to realize the fast charging; finally, the constant voltage charging is adopted to guarantee that the battery is charged to its full capacity. The advantages of this charging algorithm are shorter charging time and higher efficiency. The charger IC monitors the voltage and current in battery to confirm the charging stage.The charger IC discussed in this thesis, is designed to charge single cell lithium-ion batteries. Besides its excellent charging algorithm, both programmable time and programmable current based terminating schemes are available. A bandgap voltage reference and a current reference used in the charger are described, which has such high supply-voltage rejection ratio and good temperature characteristic that guarantees final float voltage accuracy. No external sense resistor or external blocking diode is required for charging due to the internal MOSFET architecture. Thus, the basic charger circuit requires only two external components, which simplifies the application. Internal thermal feedback regulates the charge current to maintain a constant die temperature during high power operation or high ambient temperature conditions. The structure and principle of each circuit module also are presented.The circuit is simulated via HSPICE based on 0.5um N well CMOS process, whose results demonstrate the excellent performance of the Li battery charger IC described in this thesis.更多还原