Research And Design Of Lithium Battery DC Charging Management Chip

With the continuous development of society,portable devices have almost become an indispensable part of our daily lives,and their functions are becoming more and more diversified at the same time the demand is increasing day by day.Among them,the battery as its core power supply unit is also required to continue to develop in the direction of large capacity,small size,fast charging,and high reliability.In the battery family,lithium-ion batteries(hereinafter referred to as lithium batteries)have become the first choice for rechargeable batteries in portable devices due to their green pollution-free,low cost,and long recyclable life.In addition,lithium batteries are also widely used in Internet of Things equipment,medical equipment,and even military equipment.However,due to the electrochemical characteristics of the lithium battery itself,it has to consider its safety issues during use.So far,a lithium battery charging management chip has appeared.This paper realizes the research and design of a lithium battery DC charging management chip.The main functions and implementation methods are as follows:(1)Three-stage charging.Detect the battery voltage through the voltage comparator,identify whether it is in the trickle phase,the constant current phase,or the constant voltage phase,and control the current output of the charging power tube by controlling the sampling tube(with the help of the virtual short and virtual interruption characteristics of the op amp,To ensure that the working conditions of the two tubes are the same,with a width-to-length ratio of1:1100);(2)Battery temperature protection.The temperature of the battery is actually expressed in the form of voltage,and the two are inversely proportional.In the text,the temperature of the battery is limited to a certain range through two voltage comparators.After this range,the chip is in sleep mode;(3)Chip temperature protection.The temperature protection of the chip is achieved by comparing the voltage change of the PN junction with the reference voltage.When the chip temperature rises to the first threshold voltage,the charging current is automatically reduced to reduce heat generation.When the chip temperature rises to the second threshold voltage Stop charging;(4)Power supply voltage under-voltage lockout.When the power supply voltage is too low,the chip is in a locked state rather than an incorrect working state,which is mainly achieved by a hysteresis comparator.Based on Hua Hong Hongli’s 0.18μm BCD process,with the help of cadence tools,the circuit design,simulation,layout design and verification of the entire chip circuit from the architecture design,the bottom circuit design to the entire chip circuit are completed.The simulation results show that under typical conditions,the trickle charging current of three-stage charging is about 100 m A,the trickle threshold voltage is about 2.87 V,the constant current charging current is about 1010 m A,and the constant current charging threshold voltage is about 4.15 V.The termination voltage is about 4.22V;the battery temperature protection range is 45%VCC～80%VCC;the maximum junction temperature of the chip is 165℃,and the over-temperature protection trigger temperature is 125℃;the power supply voltage undervoltage lockout threshold voltage is 3.7V.In addition,this article adopts the layout design of 1P2 M process technology,and the final chip area is controlled to only 0.6mm2,which greatly reduces the production cost of the chip.At the same time,the chip also reserves a debugging port for adjusting the output voltage value of the reference voltage part.