An automatic peak-valley current mode step-up/step-down DC-DC converter with smooth transition

This paper presents an automatic peak-valley current mode step-up/step-down DC-DC converter with high efficiency, small output voltage ripple, and fast transient response. The converter could automatically changes between peak and valley current modes by using the proposed control scheme. The switching loss is reduced by operating in pure buck or pure boost mode, and the conducting loss in transition mode is reduced by decreasing the average inductor current. The output voltage ripple is alleviated by introducing two transition modes. A fast load transient response is achieved with a small overshoot and undershoot voltage. The proposed converter has been designed with a standard 0.5μm CMOS process. The output voltage can be regulated from 2.5V to 5.5V with the input voltage in the same range. The output voltage ripple is less than 10mV in all operation modes. The maximum load current is 600mA, and the peak efficiency is 95%.