Research And Design Of Lithium-ion Battery Linear Charge Controller

Along with the mobile communication development, portable electrical applications become more and more widespread, and this requires the battery to be more suitable. Lithium-ion batteries, because of their less weight, smaller size, higher voltage and higher available energy densities than other secondary batteries, have become increasing popular for use in portable electronic devices. But Li-ion batteries require accurate charge voltage, charge current and charge temperature in charging. so it is very important to research and design high accurate, intelligent charge circuits and protect circuits.In this paper, the research and design of a high accuracy linear charge controller is presented. This controller is ideal for single cell 4.2V Li-ion batteries and lithium polymer batteries. It has a simple external circuits, it only needs a PMOSFET, several resistances and capacitances to construct a charging system. It charges the battery with three phases: pre-charge, constant current charge and constant voltage charge. The controller can detect the battery's temperature, if the charging temperature is outside the range, charging will be terminated. Also it has temperature protect circuit, current limit circuit to make sure the charging system work balanced.These circuits used chrt 0.35μm CMOS process, and the simulation software is Cadence. The simulation results show that constant current accuracy is within±1.5%, and constant voltage accuracy is within±0.5%. We also simulated the system circuits with Synopsys-saber, simulation results show that the controller can achieve it's functions.