A Synchronous Multioutput Step-Up/Down DC–DC Converter With Return Current Control

This brief presents a new return-current control method for a multioutput step-up/down dc–dc converter. Compared with prior multioutput dc–dc converters, the presently described converter can generate outputs higher or lower than the input voltage with simple control-loop compensation while guaranteeing stability in a wide load range. Using a 0.5-$muhbox{m}$ bipolar CMOS (BiCMOS) process, a converter having five outputs has been implemented for an LG active-matrix organic light-emitting diode (AM-OLED) display panel. The implemented converter operates at 1-MHz switching frequency with 4.7- $muhbox{H}$ inductor and 10- $muhbox{F}$ capacitor. Experimental results show that the proposed control method can generate tightly regulated stepped-up or -down outputs stably under a wide load variation. The conversion efficiency is higher than 80% at a typical AM-OLED panel grey level.