(电子科技大学 电子薄膜与集成器件国家重点实验室, 成都 610054)
(State key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China)
设计了一种双相位峰值电流模控制、具有大负载能力的降压稳压芯片。通过双相位的工作,保证了芯片在重载下具有较高的效率。同时,为了防止在轻载下两个相位的工作引入额外的开关损耗,提出了一种轻载模式。通过利用电流模控制模式中电压环路内误差放大器产生的控制电压来检测实际负载的大小,实现相位的切换以及在更低负载下的断续导通降频工作模式。基于0.35 μm BCD工艺进行仿真设计。仿真结果表明,在输入电压12 V,输出电压1 V,开关频率500 kHz,最大负载20 A下,与传统单通道峰值电流模比较,重载20 A下的效率可以提升3个百分点,轻载0.5 A下的效率可以提升10个百分点。
A dual-phase peak current-mode control buck converter chip with large load capability was designed. By operating in dual-phase, the chip was guaranteed to hold high efficiency under heavy load. Considering the extra switching loss from two phases during light load, an optimized light load mode was proposed. It used the control voltage generated by the error amplifier in the voltage loop of the current-mode control loop as the load position detector. When the load was stepped down, the active phase could be changed from two to one. As the load turned into ultra-light, the system could also work in discontinuous conducting mode to further improve the efficiency. It was designed in a 0.35 μm BCD process. Simulation results show that under the conditions of 12 V input voltage, 1 V output voltage, 500 kHz switching frequency and 20 A maximum load, compared with the traditional single-phase peak current-mode, the maximum efficiency can be improved by about 3 percentage point under a heavy load of 20 A and can be improved by about 10 percentage point under a light load of 0.5 A.