Quasi-SM controller for SIDO buck converter with self-adaptive free-wheeling current level

A Single-Inductor Dual-Output (SIDO) buck converter with a novel quasi-sliding mode (SM) controller is presented in this paper. Instead of keeping as a constant current, the free-wheeling current level can vary according to the load condition to extend the load range while maintaining high power efficiency and less cross regulation at the same time. To verify the feasibility of the proposed technique, a SIDO buck converter with two regulated output voltages, 1.8V and 3.3V, is designed and fabricated in HEJIAN 0.35 μm CMOS process. Simulation and experiment results show that the cross regulation can be reduced to as low as 0.057 mV/mA when the load changes from 50mA to 100mA.