A novel method for smooth transition in step-up/step-down DC-DC converter

This paper presents a step-up/step-down converter with a novel control scheme based on noninverting buck-boost converter. The control scheme is used to obtain a transition mode and implement smooth transition between buck mode and boost mode. The transition mode is adopted to improve the linearity between the output voltage and the control voltage. With the proposed control method, the output ripple voltage is significantly reduced when the input voltage is close to the output voltage. In addition, this method decreases the complexity in circuit design and enhances efficiency. The step-up/step-down converter has been designed with 0.5 ¿m CMOS process, and can regulate an output voltage within the supply voltage ranged from 2.5 V to 5 V. The simulation results show that the output ripple voltage in the transition mode is less than 3 mV which is smaller than that in the buck mode and boost mode.