Adaptive On-time Buck Converter with Virtual Inductor Current

• Main Authors: Mao-Hui Kuo, 郭茂輝
• Other Authors: Huang-Jen Chiu
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/84773282526775964881

碩士 === 國立臺灣科技大學 === 電子工程系 === 105 === In this thesis, adaptive on time and virtual inductor current ripple control schemes are proposed to improve the variation of switching frequency in different loads and unstable. In general, ripple-based constant on-time (RBCOT) control requires the use of large equivalent series resistance (ESR) of the output capacitance to effectively control system. However, the proposed virtual inductor current ripple control scheme can use low ESR of the output capacitance. The switching frequency of RBCOT control changes when the load current is different. The on time of proposed adaptive on time scheme can be adjusted to maintain a constant switching frequency by detecting the load current. The chip had been implemented with TSMC 0.35-μm 2P4M CMOS technology and its chip size including pads was 1.49×1.49 mm2. The input voltage is 3.3V and output voltage is 1.8V. The off-chip inductance and capacitance are 6.8 μH and 10 μF, respectively. Simulated results show that the variation of switching frequency is around 10 kHz when the ESR of the output capacitance is 10 mΩ and the load current varies from 100mA to 500mA.