A PFC Single-Coupled-Inductor Multiple-Output LED Driver Without Electrolytic Capacitor

In order to lower the system cost and reduce the form factor, single-inductor multiple-output (SIMO) converters are intensely developed for on-chip DC-DC converters and off-line light emitting diode (LED) drivers. However, existing single-stage power factor correction (PFC) SIMO LED drivers are usually designed with electrolytic capacitors, leading to a short life span and limited range of operation temperature. In this paper, based on a single dual-winding coupled inductor, a SIMO LED driver with PFC function is proposed without the requirement of electrolytic capacitors, where a small storage capacitance is used to actively decouple the ac and dc input powers. Compared with previous works, the proposed PFC SIMO LED driver has some additional benefits, including a smaller line filter, multiple output currents without double line frequency ripple and a faster output regulation. With appropriate control strategy, an independent output regulation can be achieved for each output channel. Meanwhile, to improve the converter efficiency, the energy flow of the converter is optimized with an inductor current programming technique. Finally, the proposed electrolytic capacitor-less PFC SIMO LED driver is developed, designed, tested and compared with a single-stage SIMO design without active power decoupling.