A KY Buck-Boost Converter with Extended Ramp Control Achieving 1500% Output Variation Reduction for Smooth Mode Transition

In this paper, a KY buck-boost converter with extended ramp control for the Li-ion battery in the mobile applications is presented. Conventional non-inverting buck-boost converter suffers from several issues, including high conduction loss due to the excessive average inductor current and right-half-plane (RHP) zero existence which degrades the system stability and the transient performance. A KY buck-boost converter is a good candidate to relieve these problems. Unlike the conventional triple mode control utilized in the buck-boost converters, the proposed extended ramp control can achieve smaller output voltage fluctuation when the input voltage is close to the output voltage. The chip prototype is designed using a TSMC 0.18um BCD process. Simulation results show that compared with triple mode non-inverting buck-boost converter, 1500% output voltage fluctuation reduction (less than 10mV) during mode transition is achieved in the proposed control. The peak efficiency of this work can achieve 95.1%.