Lowest-Voltage-Switching and Zero-Voltage-Switching Control for Buck Converter

• Main Authors: Chu-Yi Chiang, 姜柱圯
• Other Authors: 陳秋麟
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/68830049900111453144

博士 === 國立臺灣大學 === 電子工程學研究所 === 97 === A new integrated circuit approach for Lowest-Voltage-Switching and ZVS control is presented for PWM buck converters under DCM/CCM boundary mode. This proposed technique compensates control circuit delay and hence turns on the power MOS at the exact instant of lowest/zero drain-to-source voltage. No complicated timing calculation circuits or additional external components are required. This proposed integrated Lowest-Voltage-Switching and ZVS control can be applied to other DC-DC converters as well. Circuit analysis, implementation and the die photo are shown. Experimental results for an example circuit with VIN of 5V and VOUT of 1.8V and 3.3V reveal that buck converters with the presented Lowest-Voltage-Switching and ZVS technique have higher efficiency than conventional ones, especially at higher frequencies. At about 1.35MHz and 3.6MHz operation, the measured conversion efficiency of the PWM buck converter under DCM/CCM boundary mode with the proposed Lowest-Voltage-Switching and ZVS approach is 9% and 11% higher, respectively. Also, the replenishing scheme for the holding capacitor in sample and hold circuit is designed and simulated. Its operation is analyzed and simulation results are illustrated. Furthermore, buck converter with synchronous rectifier and its related ZVS gating control is presented. Analysis and simulation results are conducted and shown.