高精度多模式锂电池智能充电管理芯片的设计

发布时间：2018-10-24 06:12

【摘要】：随着IC技术的发展,手持设备的种类和数量日益增多,而作为手持设备的核心,电池被赋予的期望也变得越来越高,传统储能电池的不足开始显现出来。新兴能源锂电池以其比能量高、无污染、容量大、循环寿命长等优点被称为21世纪发展的理想能源并成为当今市场上储能设备的主流。但是锂电池在使用时也有着备受关注的安全性问题:过充电以及高温都会使锂电池有发生爆炸的危险;过放电会减少锂电池的寿命甚至会损坏锂电池。在锂电池充放电期间对其采取一定的保护措施是非常有必要的,因此对高可靠性、高精度、安全快速的电池充电管理芯片的研究具有十分重要的意义。本设计采用CSMC 0.5um BCD工艺,根据Buck型开关转换器的工作原理,分析并设计了一款高精度多模式的锂电池智能充电管理芯片。本文所设计的锂电池充电管理芯片对锂电池充电时采用三段式充电模式:预充电涓流模式,恒流模式以及恒压模式。由于涓流模式充电使系统工作在非连续导通模式(DCM),而恒流模式充电时系统工作在连续导通模式(CCM),因此本设计采用峰值电流模脉冲混合调制模式(PFM-PWM)控制方式,以提高对电源电压与负载变化的瞬态响应能力和系统的转换效率。为了能够适应宽的输入电压范围,引入了斜率补偿技术,增加了系统的带载能力;此款芯片最大可编程充电电流高达2A并可外部设定安全充电时间,实现了与用户的交互式管理;同时通过修调技术使电池充电终止电压精度高达±0.75%,且可外部设定对一节或者串联的两节锂电池进行充电。本设计还根据日本电池协会颁布的安全规范集成了NTC电池温度实时监测调整充电电流以及充电终止电压的充电模式。此外,芯片集成了逐周期限流保护电路、芯片过温保护电路、电池过充保护电路,坏电池检测等保护电路,提高了充电速率的同时又确保了锂电池充电的安全性。文章首先介绍了锂电池的发展历程、锂电池的充电原理和充电方法以及现在市场上应用比较多的充电管理芯片,然后阐述了Buck型开关变换器的原理和特点,对比了电流控制模式和电压控制模式的优缺点,再根据Buck型开关变换器的基本拓扑架构对系统的稳定性进行了分析。最后在此基础上设计出本文所述整体电路。本文重点分析了带隙基准电路、振荡器以及斜率补偿电路、NTC电池充电保护电路、恒流/恒压运算放大器及充电模式切换电路。在尽可能减少外围器件的前提下设计整体电路。最后,本文设计的电路在cadence平台的spectre仿真环境下进行仿真验证,仿真了在不同的输入电压、不同的工艺参数、不同的工作环境温度等条件使用电压源模拟电池充电的情况,仿真结果均满足设计指标的要求,现已送出流片。
[Abstract]:With the development of IC technology, the variety and quantity of handheld devices are increasing day by day. As the core of handheld devices, the expectation of battery is becoming higher and higher. Because of its high specific energy, no pollution, large capacity and long cycle life, lithium battery is regarded as the ideal energy for development in the 21st century and has become the mainstream of energy storage equipment in the market today. But lithium batteries also have concerns about safety: overcharging and high temperatures can cause them to explode; overdischarge can reduce their life and even damage them. It is very necessary to take some protective measures for lithium battery during charging and discharging, so it is very important to study the battery charge management chip with high reliability, high precision and safety. According to the working principle of Buck switch converter, a high-precision and multi-mode intelligent charge management chip for lithium battery is designed and analyzed by using CSMC 0.5um BCD technology. The lithium battery charge management chip designed in this paper adopts three charging modes: precharge trickle mode, constant current mode and constant voltage mode. Since trickle mode charging makes the system work in discontinuous on-mode (DCM), and constant-current mode charging in continuous on-mode (CCM), this design adopts peak current-mode pulse hybrid modulation (PFM-PWM) control mode. In order to improve the transient response to the change of power supply voltage and load and the conversion efficiency of the system. In order to adapt to the wide input voltage range, the slope compensation technology is introduced to increase the load capacity of the system. The maximum programmable charging current of this chip is up to 2A and the safe charging time can be set externally. At the same time, the terminal voltage precision of battery charging is up to 卤0.75 and can be set externally to charge two lithium batteries in one section or in series. According to the safety specification issued by Japan Battery Association, the NTC battery temperature real-time monitoring and adjusting charging current and charging termination voltage charging mode are integrated. In addition, the chip integrates the protection circuits such as periodic current limiting protection circuit, chip over-temperature protection circuit, battery overcharge protection circuit and bad battery detection circuit, which improves the charging rate and ensures the security of lithium battery charging. This paper first introduces the development of lithium battery, the charging principle and charging method of lithium battery, and the charging management chip which is widely used in the market now, and then describes the principle and characteristics of Buck switch converter. The advantages and disadvantages of current control mode and voltage control mode are compared, and the stability of the system is analyzed according to the basic topology of Buck switching converter. Finally, the whole circuit is designed on this basis. This paper focuses on the analysis of bandgap reference circuit, oscillator and slope compensation circuit, NTC battery charging protection circuit, constant current / constant voltage operational amplifier and charging mode switching circuit. The whole circuit is designed on the premise of reducing the peripheral devices as much as possible. Finally, the circuit designed in this paper is simulated under the spectre simulation environment of cadence platform. The voltage source is used to simulate the battery charging under different input voltage, different process parameters and different working environment temperature. The simulation results all meet the requirements of the design index, and have been sent out of the flow sheet.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912

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