Design Of High Efficiency Boost White LED Driver With Wide Range PWM Dimmin

Extensive attention has been payed to light emitting diode(LED),as its advantages of high brightness, high luminous efficiency, friendly for environment, long usage life and excellent spectrum charactristic, which make it to be the next generation of ideal lighting source. Nowadays, application of LED including:one is low brightness ocassion includes backlighting of cell phone keyboard, PADs such as small portable electronic products backlighting, camera flash, etc.; Another is high brightness illumination applications, including traffic lights, large plane LCD back-lighting, automotive lighting, indoor and outdoor lighting. So more space is provided for LED drivers due to the rapid expaded of LED application market. Wheras DC-DC switch power supply chip gradually come to be the best choice of LED driver with its excellent conversion efficiency.A high efficiency step-up White Light Emitting-diode (WLED) driver with PWM dimming is presented in this paper. The input voltage of this driver ranges from2.5V to5.5V, with40V (max) output voltage and260mA (max) output current,respectively. So it can easily drive one or more series WLEDs.The driver operates in asynchronous mode with an integrated N-channelPower MOSFET.The chip operates in peak current mode with a low power dissipation current sensing module. It contains PWMdimming function and the output current can be adjusted conveniently.The proposed driver is designed with CSMC0.5um40V bipolar-CMOS-DMOS process. Simulation results verify the functionality of the design and high efficiency is realized. Load current can be adjusted adaptively with dimming frequency ranges from200Hz to200KHz.The total efficiency achieves more than90%,and a peak value of94.12%can be reached at5.5V-input and200mA-load.