Design Of A Led Driver With Low Startup Power Consumption

We have to consider the strategic issues of energy saving because of globalwarming and excessive consumption of energy resources, the gradual development ofthe lighting energy makes the advent of LED lights, incandescent lamp has beeneliminated forcefully in many countries and regions in the world at present, meanwhilepeople began to promulgate policies to accelerate the development of the LED lights.However, for the LED driver, power dissipation especially the dissipation of startupmay affect efficiency of the chip.The goal of this project is to design a LED driver chip which has the characteristicof low startup power consumption, no electrolytic capacitor, pulse current driving. Thehigh voltage startup circuit of the chip provides the initial constant charging current forCVCC, and the charging current can be adjusted to control through the internal resistance.There’s low power dissipation after the completion of startup, so it won’t influencechip’s efficiency. We separate analog, digital power supply to reduce the interference ofdigital signals to analog power supply，and the voltage of the drive power supply is high,so it can reduce the loss of switch. The PWM module of the chip controls the switchduty to keep output stable using current mode, which is based on the output samplingfeedback, We design level shift circuit to heighten the low voltage, the driving stageprovides the drive capability for the switch, and the dead time control circuit reduces theloss of switch.This paper first introduced the development of electric light source and theappearance of LED, followed expounded driving characteristics and varies of topologyof LED driver, then designed part modules of the chip and external parameters, theresults of simulation verified the expected requirements, finally designed the layout ofthe chip.