A high efficiency single-inductor dual-output buck converter with adaptive freewheel current and hybrid mode control

摘要

A single-inductor dual-output (SIDO) buck converter with adaptive freewheel current and hybrid mode control is presented in this paper. It operates in pseudo-continuous conduction mode (PCCM) with single freewheel phase to reduce switching loss and minimize cross regulation. Freewheel current adjustment is implemented by detecting and control freewheel time, which can extend the load range and improve efficiency. For unbalanced load, this paper further proposed a hybrid PWM/hysteretic mode control scheme, which enables the two sub-converters to work at their own mode based on the load, independently of each other. The converter was designed with a 0.18μm CMOS process. Simulation results show that the efficiency reaches 87% in PWM mode. At light load, it is still higher than 80%.