| Li-Ion batteries are the standard power source for today's electronic products, especially for portable appliances such as notebook computers, mobile phones, and digital cameras. Li-Ion battery has advantages such as high operation voltage, high power density and little self-discharge rate. However, it's very sensitive to the voltage of itself. Over charge or over discharge will cause problems to the normal operation. Thus, a charger with safe, reliable, fast and high efficiency is important for the performance and application of the battery. In this thesis, the chemic structure, performance and charging scheme of Li-ion battery are studied. And based on the effect of charging process, some problems are introduced, and as a solution, a linear charger IC for single Li-ion battery is designed.So far, there are four primary approaches for the charging of Li-Ion battery: Constant Current (CC) mode, Constant Voltage (CV) mode, Constant Current Constant Voltage (CC/CV) mode and Pulse mode. Following the operational principle of the Li-ion battery fast-charging and the existing charging approaches, we choose CC/CV mode here. Pre-charge the battery with a trickle current at the initial of charging cycle to fix and protect the over-discharged battery. After that, the battery will be charged with a large constant current to allow fast charging. Finally, the constant voltage charging is adopted to guarantee the battery be charged to its full capacity.In this thesis, the basic knowledge about Li-Ion battery charger is introduced first, then, the system structure and a Li-Ion battery macro mode is described. After that, the idea about high precision is discussed. Finally, the charge control circuit design and realization are emphasized. The charger IC is based on CSMC 0.6μm CMOS process, and the Spectre simulation results indicate that performances of the charger meet the prospective specifications perfectly.
|
PDF Full Text Request