Research And Design Of High Efficiency And High Accuracy Switching Lithium-ion Battery Charger Chip

Lithium-ion batteries have the advantages of high energy density,high operating voltage,long life cycle,no memory effect,and light weight,and have been widely used in various electronic products and devices.In order to save energy,prolonging the service life of lithium-ion batteries has become the goal of everyone's research.The special structure of lithium-ion batteries is particularly demanding for charging.During the charging process,over-temperature,over-voltage,etc.will damage the lithium-ion battery and directly affect the service life of the lithium-ion battery.Therefore,a fully-protected lithium ion is designed.The battery charger chip can effectively utilize the battery capacity,prevent the battery from being damaged,and prolong the battery life.Based on the principle of Buck-type switching power supply converter,this article uses NEC 0.35?m BCD process to design a high-efficiency and high-precision switching lithium-ion battery charger chip.The chip integrates various protection circuits such as overvoltage and overtemperature.Ensure the safety of lithium-ion battery charging process.The chip is designed with constant current charging and constant voltage charging and two charging circuits sharing one compensation circuit,which saves chip area and power consumption.Two loops cannot work at the same time,one loop works,and the other loop pair The system does not work,and is controlled by the output of the error amplifier in the two loops.The two error amplifiers are connected to the same output.When the output of the error amplifier in the constant current charging loop is active,the chip is turbulent or constant current charging;When the output of the error amplifier in the constant voltage charging loop is in effect,the chip is charged at a constant voltage,and the two charging loops can transition smoothly.According to the charging modes of the two loops,different modulation modes are adopted to improve the conversion efficiency,charging accuracy,and response speed of the system.In constant current/constant voltage charging,PWM current control mode is used;in trickle charging,PFM current control mode is used.Through the Cadence software platform,the overall circuit design and simulation are completed.The input power is designed to be 5V,the switching frequency is 1MHz,and the switching charging efficiency is 90%.The charging is divided into three stages and the charging threshold voltage is set to 2.9V.When the battery voltage is less than 2.9V,the trickle charge current is 0.2A.When the battery voltage rises to more than 2.9V,the constant current charges 2A,and the charging current accuracy is ±4%.When the battery voltage rises to a float voltage of 4.2V,the system is charged at a constant voltage,and the voltage accuracy reaches ±0.5%.At constant voltage charging,the charging current decreases until the end of charging.