Research And Design Of Multiple Backlight LED Driver Chip

LED technology is recognized as the21st century a new generation of lightingtechnology, has very broad prospects for development. Backlight LED applicationsdeveloped rapidly, a wide range of applications in fields such as mobile phones,computers, home appliances, automotive electronics. The rapid development of LEDapplication, LED driver technology brings higher requirements.LED backlight is phasing out the traditional CCFL backlight backlight field.Widely used in a large-size screen with backlight LED driver chips are increasing, thenumber of LED driver also gradually increase, and requires the ability to supportmultiple current balance, multiphase boost and multiphase dimming control.In response to these needs, this article is based on CSMC0.5um DPTM CMOStechnology library designed of a multiphase white LED driver and current balancecontrol chip, constant current output, multi-channel current balance, boostcompensation, phase shift, and dimming functions, The two methods of work andself-oscillation and external synchronization. Multiphase boost converter chip driveoutput, in order to significantly reduce the switching power supply output voltage ripple;multiphase buck converter design flexibility to drive the3,4,5and6parallel LEDstrings load each branch less than3%of the current balance accuracy while achieving;using a low-frequency PLL design, support external PWM dimming signal or internalself-oscillating clock signal, to achieve precise PWM dimming; and can automaticallydetect multiple parallel the LED branch number of dimming to achieve a correspondingnumber of phase shifted signals, and reached a precision backlight LED drive the whitebalance control.This paper first introduces the LED light-emitting principle and characteristics, aswell as backlit LED characteristics and trends; next connection of LED applications,dimming and LED driver; then introduced multiple backlight LED driver chip researchand design, and build the system architecture, and highlights from the system point ofview, the boost control system, current balance, control systems and dimming systemworks three modules; then details three systems various sub-modules of the circuit structure and function; Finally, do the whole circuit the CORNER simulation and theparameter simulation, and the simulation results show that the output voltage ripplechanges in the range of less than5%; current change in the range of less than3%, toachieve the studyand design expectations.