A Limited Maximum On-Time Switching Based Li-ion Battery Charger with Dual-Loop Mixed-Mode Smooth Transition
|關鍵字:||鋰離子電池;充電器;平滑轉換;Li-ion battery;charger;smooth transition|
本論文呈現兩顆充電晶片，皆透過台灣積體電路公司提供之0.35微米標準互補式金氧半製程實現，最後量測之整體晶片面積為1.647mm *1.365mm，功率電晶體操作切換頻率設定1MHz，輸入電壓為5V，充電器輸出電壓為4.2V ~ 4.8V，量測之充電功率可以達到83%。|
After entering the 21st century, along with the demand trend of portable devices, smart phones, tablet PCs, notebook computers, and other devices have gotten very popular quickly. All devices become an indispensable portable tool for everyone. In recent years, rechargeable batteries are main energy supply of intelligent portable devices, and as one of the energy carrier supplies, lithium-ion battery naturally in today's technology development plays an important role. At the same time, in order to keep up Lithium-ion battery produced by a variety of specifications and performance requirements, the specifications of charging system design have gradually become more and more complicated than it used to be. In addition to the requirements for high energy conversion efficiency, the charging system must consider reducing the charging time as much as possible, while avoiding from overcharging the battery. There is no doubt that several topics are very important for the lithium battery charger design, such as charging multiple output targets, reducing the size of the charging system, achieving stability of the whole system, smoothly providing energy to the battery, and so on. This paper takes into account the future trend of intelligent electronic products and the use of the switching regulator as infrastructure so that the need for higher energy conversion efficiency and less energy consumption for the battery charge can be achieved. Considering battery specifications, this design extends the buck converter circuit to achieve the required charger specifications. Furthermore, to have the efficient charging process successfully implemented, the charger limits the maximum on-time of power MOS and uses a voltage-current mixed-signal smooth conversion method to reduce the ripple between the charging mode switching. The charger also utilizes adaptive closing time control to reduce the ripple in the last stage of the charging process. The two charger chips presented in this thesis were fabricated by TSMC 0.35μm mixed‐signal CMOS process. The overall chip area is 1.647mm * 1.365mm and the switching frequency of the power transistor is 1MHz with the supply voltage of 5V. The output voltage is 4.2V ~ 4.8V and the measured charging efficiency can reach 83%.