Design of Control IC for Multiphase Buck Converter

• Main Authors: Ji-ShiangLee, 李吉祥
• Other Authors: Tsorng-Juu Liang
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/50891436630827474926

碩士 === 國立成功大學 === 電機工程學系 === 102 === In this thesis, a controller for a multiphase DC-DC buck converter with alternate phase-shedding is realized. The current mode control is adopted in this controller for achieving current sharing, adaptive voltage position, and phase-shedding function. With phase-shedding control, the efficiency at low load condition is improved by turning-on appropriate number of phase(s), but the temperature on the active phase(s) is higher than the off phase(s) that cause the temperature unevenly distribution. To solve this problem, the alternate phase-shedding is implemented in the proposed controller. The phases take turns to provide the load current at low load condition to distribute power to each phase and share the same load as well as improve reliability. The proposed controller would implement interleaved control regardless the number of active phases. In addition, taking advantage of the application of high step-down ratio, the proposed control structure that input current is sensed to control each phase is adopted. The number of components and pins of controller can be reduced. This chip is fabricated with TSMC 0.25um CMOS high voltage mixed signal general purpose process and is tested with an input voltage of 12 V, output voltage of 1.2 V, and output power of 72 W three-phase buck converter to verify the feasibility.