A Charge-Recycling Buck-Store and Boost-Restore (BSBR) Technique With Dual Outputs for RGB LED Backlight and Flashlight Module

A boost converter with buck-store and boost-restore (BSBR) technique fabricated by 0.25 mum CMOS BCD process can provide different supply voltages to drive series red, green, and blue LEDs in sequence for reducing the power consumption on the constant current generator. The proposed technique not only stores and restores extra energy during the transient time of the reference tracking response to improve the efficiency but also enhances the reference tracking response to greatly reduce load transition time. Experimental results show that the period of reference tracking response can be improved. When the load current is 100 mA, the periods of reference down-tracking and up-tracking are smaller than 10 and 20 mus, respectively. Furthermore, this technique can also provide a regulated voltage to drive the subblock implemented in the liquid crystal display system. The maximum efficiency of charge recycling is up to 94%, and the maximum efficiency of this boost converter is 94.5%. Experimental results demonstrate fast and efficient reference tracking performance is achieved by the proposed BSBR technique.