限制最大導通時間之雙迴路混和模式平滑轉換切換式鋰電池充電器

Abstract

進入了21世紀之後，伴隨著世界的各種行動裝置需求趨勢，如智慧型手機、平板裝置和筆記型電腦等設備迅速的普及化，近幾年更是成為每個人不可或缺的隨身工具。目前的智慧型攜帶裝置其主要供應能源大多還是以充電電池為主，而做為其中之一的供應能源載體，鋰離子電池自然也在現今科技發展中扮演著重要的角色；與此同時為了因應鋰離子電池所產生的各種規格與性能需求，對於該如何把能量有效的存進電池內，充電系統的設計規格要求也逐漸地變得比以往電路來的更加複雜。 本論文考量到未來相關智慧型電子產品趨勢，需要較高能源轉換效率，故採用切換式鋰離子電池充電器作為基礎架構，使外部能源能夠在較少的損耗下為電池進行充電；並考量到電池本身規格，本次設計延伸降壓變換器電路來達到所需之充電規格。同時為了使充電過程能順利執行，電路限制最大導通時間，並採用混合電壓電流模式平滑轉換方法，達到控制功率電晶體開通時間，解決充電模式間切換時的模式震盪；另外設計電路使用適性關閉時間控制方法，減少電路充電後期的大振福漣波所造成的雜訊干擾。 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%.