| Because of small size, light weight, long life and high energy densities, Li-ion and Li-polymer battery have become increasingly popular in portable electronic devices. Charger is an important component in the battery power management system. In order to charge battery safely, reliably, fast and efficiently, based on the Li-ion and Li-polymer battery's character and general charging method, a charger IC for single Li-ion or Li-polymer battery is designed.The charging mode based on the CC/CV has been adopted, in which the process has been divided into three phases. At the first phase, the battery is pre-charged with a trickle current to repair and protect the over-discharged battery; at the secondary phase, the battery will be charged by a large constant current to allow the fast charging; at the last phase, the constant voltage charging is adopted to guarantee the battery fully charged. The particular characteristic of this IC is high applicability, because its power supply can use different adapters or USB ports, especially when using the current-limited adapter, it integrates the advantages of linear charging mode and pulse charging mode, which improves charging efficiency. Besides, the modules such as the chip temperature control, battery temperature detection and protection, power status detection and charge timing are also added to the system to allow the intelligent control of the charging process.The process of 0.5μm CMOS with N well has been applied, which reduces the cost. Through HSPICE simulation, battery's final float voltage reaches 4.1V±0.56% at different process corners, the temperature between -40℃and 125℃, and input voltage between 4.3V and 6.5V. The charging efficiency is up to 96% in constant current charging phase when the IC is supplied by a current-limited adapter whose limited current is 0.5A. This IC simplifies the outside circuit so that it can accomplish all the charging functions only at the cooperation of few additional capacitances and resistances.In this paper, the composition and chemical principle of the Li-ion and Li-polymer battery are firstly presented, which are followed by their characteristic and common charging approaches introduction. And then, the whole structure and principle of this chager is illuminated. At last, the design and realization of actual circuits are emphasized, the HSPICE simulation results are provided as well. |
