Design Of White LED Driver Circuit With High Efficiency Based On The Charge Pump

One important element of consumer electronics backlight system is white LED backlight driver IC. In mobile phones, MP4, laptops, LED TV, and other consumption electronic products, white LED backlight driver IC is widely used, which can be called a bridge between portable batteries and LED backlight unit. However, as the reduction of size of consumer electronics and a portable battery, white LED backlight driver IC based on traditional three-mode charge pump cannot meet the requirements of the future consumer electronics.In order to enhance the efficiency of white LED backlight driver IC, the paper adopts a new four-mode 1x/1.25x/1.5x/2x charge pump, while its control circuit are proposed,and embedded in white LED driver chip. The main contents of this paper include:A new four-mode 1x/1.25x/1.5x/2x charge pump is adopted, which can provide 1 times, 1.25 times, 1.5 times and 2 times step-up features.A new type of 1x/1.25x/1.5x/2x four-mode charge pump control circuit is designed,which can automatically adjust the operation mode of charge pump.A novel band gap reference core circuit which alleviates current-mirror mismatch error distinctly is proposed. With help of low power design technique and a unique start-up technique, a band gap reference circuit with ultra-low power consumption is designed.Finally, use the Synopsys Hspice simulation software with SMIC 0.5μm BiCMOS model to simulate, from the results, we can see that efficiency of this white LED backlight driver IC can reach 70%～90%,above 90% highest. Simulation results can meet the development requirements of chip performance.