Design Of High Efficiency Self-adapted Charge Pump White LED Driver XD9107

The design work in the paper is on the basis of the project"Theoretical research and design of key technique for power management IC". Based on electrical characteristics, through systematic design, circuit design and performance simulation, a high efficiency self-adapted charge pump white LED driver XD9107 is designed to drive four Main LEDs for back light and one high current LED for camera light.This paper analyzes and studies the principles of white LED driver and charge pump converter which are the theory guidance to the design and implementation of XD9107. The system adopts fractional charge pump structure, and through controlling the state of power switch, makes the chip have three work patterns including 1x, 1.5x, 2x. The chip starts up in 1x mode, and offers automatic boost-mode switching when the signal of LED current source dropout is detected, which prolongs the effective working time of Li-Ion battery. Dual outputs make it possible that the full-scale current through the LED can be independently programmed via external resisters. The LED current is controlled by strobing two pins via internal counter and DAC, therefore the brightness of LED can be adjusted. Besides, XD9107 has built-in functions of over-temperature protection, over-current protection and open-loop protection.After completing the operational principle and designing of the circuits, the function performance and key characteristics of XD9107 and its sub-blocks, are simulated based on the 0.6μm BiCMOS process from a company abroad using Cadence software. The simulation results verify the correctness of theory and the feasibility of the design method, and can meet the prospective specifications.