节点文献
单片锂电池充电管理芯片的设计
【作者】 刘杰；
【导师】 陈勇；
【作者基本信息】 电子科技大学 ， 微电子学与固体电子学， 2010， 硕士
【摘要】 随着现代电子技术的发展,电子设备日益趋于便携化的同时对他们的供电电池也提出了轻便、高效的要求。锂离子电池正是以其能量密度高、供电电压高、无记忆效应、无污染的特点逐渐取代传统的镍镉、镍氢电池、铅酸电池被广泛应用于现代便携式电子产品中。相对于其他化学电池,锂离子电池在性能优异的同时也显得更为精致和脆弱,因此对锂电池充电过程的控制要求更为严格,需要高精度的电压、电流设置,分阶段的充电模式和完善的保护电路。本论文设计了一款适于对各种锂电池充电进行管理的电流控制模式PWM开关电源芯片。芯片对锂离子电池的充电过程设有恒流模式、恒压模式及BURST模式以保证充电过程的高效和节能。当电量释放完毕的锂离子电池被置入芯片作为负载时,系统自动检测并选择一个恒定的较大的电流进行充电,此阶段芯片工作占空比不变,工作频率随着电池电压的升高而升高;电池电压接近设定的终止电压时转为恒压充电模式,芯片开始减小占空比,充电电流亦随之减小,工作频率稳定不变;电池电压达到终止值时系统将关闭以防止电池过冲对其自身带来的损伤。当电池电压由于某种原因下降时,系统自动进入BURST模式,以较低的工作频率、小的电流对电池电量进行缓慢地补充。芯片内置了逐周限流电路、过压保护电路及欠压锁定电路以保证芯片安全运行。论文首先对锂离子电池特性和开关电源原理的简要说明,然后介绍了芯片各模块并对关键模块给出了设计过程和仿真结果,最后对芯片整体运行的各个工作模式进行了仿真。芯片采用了CSMC 0.5um BCD工艺,在仿真方面使用的是Cadence的Spectre仿真工具。
【Abstract】 With the development of modern electronic technology, electronic devices tend to be portable. This trend also made their batteries portable and efficient. Lithium-ion battery with its high energy power density, high power supply voltage, no memory effect, no pollution gradually replace the traditional nickel-cadmium, nickel metal hydride batteries, lead acid batteries are widely used in modern portable electronic products. Compared with other chemical batteries, lithium-ion batteries have excellent performance and also more delicate and fragile therefore the charging process must be strictly controlled. They require high accuracy voltage and current settings, different charging mode and comprehensive protection circuitry.This paper designed a current control model PWM switching power supply chip. It is suitable for the charging management of all kinds of lithium batteries. In order to ensure efficient charging and energy saving, this chip offers constant current mode, constant voltage mode and BURST mode. When the completely released lithium-ion battery is placed in chip as its load, the system automatically detects and chooses a larger constant current to charge the battery. At this stage, duty cycle is constant and the operating frequency increased as the battery voltage rises. When the battery voltage approaches the termination value, the chip enters into constant voltage charging mode. The system began to reduce the duty cycle, the charging current also reduces. At this stage chip works in the same frequency. When battery voltage reaches the termination value, the system will shut down in order to prevent battery damage caused by its overshoot. When the battery voltage falls for some reason, the system automatically enters BURST mode. The chip work with lower frequency, lower current to complement battery energy slowly. Cycle-by-cycle current limit, OVPT and UVLO circuit are built-in the chip to ensure the safe operation of chips.Firstly, this paper characteristic of lithium-ion battery and a brief description of the principle of switching power supply; secondly, introduced each module of the system and for the key modules we give the design process and simulation results; finally, each operating mode and the overall operation of the chip are simulated. This chip is build on CSMC 0.5um BCD process and used in the simulation is Cadence Spectre simulation tools.