A Switching Buck Converter with Improved Light-load Efficiency

• Main Authors: Chien-Erh Liao, 廖建貳
• Other Authors: Chung-Hsun Huang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/dah89q

碩士 === 國立中正大學 === 電機工程研究所 === 104 === In this thesis, existing MPET(Maximum Power Efficiency Tracking Technique) to improve power conversion efficiency in CCU LPIC lab. is investigated to design power efficiency tracking fuction for wide load operative range and high light-load efficiency. There are two major directions to improve power conversion efficiency for existing technology of buck converter in CCU LPIC lab, SOM(Switch-On-Demand Modulator), and MPET. The former focuses on improving medium or light-load efficiency, and the latter focuses on light or ultra light-load status. In the first edition MPET which based on SOM , it was concerned when is the appropriate time to shut down the circuit block which without work. The method depends on counting the numbers of CLK which had been masked. It is unsuitable that it will change as the whole circuit system change, and it’s hard to start the mechanical cut-off at the appropriate time. In this condition, it will cause the power consumption to diminish its efficiency. Regarding the above discussion, this thesis proposes the second edition MPET which is called Real-Time Maximum Power Efficiency Tracking Technique. It can track power efficiency for wide load operative range on accuracy time. It can not only find the right time to shut down circuit, but also suit with circuits made of different designers. The technique solves the flaw that is the first edition MPET just suitable for unique circuit, and improves light-load efficiency effectively. The principle is design a circuit to compute the input and output power, and maps to one power conversion efficiency line which vary from load status. Furthermore, it can monitor power consumption in control stage circuit blocks. Once the efficiency line is below a threshold voltage, it will mean static loss is dominated in whole power loss. At the moment we shut down the circuit blocks which without work. Further, this thesis design a Energy Self-supply circuit, it can supply energy to load automatically in ultra light-load and open loop status if the power hungry ampilier is shut down. We couled achieve the purpose that output voltage is stable and static loss can be decreased, it makes the Light-load Efficiency better, the buck converter combinated with SOM and RT-MPET operates in the wide load range and maintains high power conversion efficiency. Finally, this buck converter chip is designed and fabricated with TSMC 0.18μm 1P6M 3.3V Mixed Signal process technology. The chip use the improved version for maximum power efficiency tracking technique. This technology can operate in the wide load range, and track power efficiency for high light-load efficiency. In this thesis, light-load efficiency is over 72%, and operate from 1mA to 500mA load current.