Designs Of Boosting LED Drive Circuit That Base On PWM Control

With the rapid development of semiconductor materials and electronic technology, LEDbecause of its high efficiency, long life characteristics, becoming widely used. Because theLED with the input voltage and temperature variations caused by changes in light intensityLED occur, leading to changes in brightness, therefore, how to design efficient and stablevoltage LED driver circuit, has become a hot topic of research.In this paper, lithium battery and5V power supply of mobile devices, analysis andcomparison, the improvement of existing LED voltage driver circuit, designed based onBOOST type DC-DC boost, peak current mode PWM modulation mode LED driver circuit.The driver circuit based on the voltage control loop, add a current control feedback loop,forming a voltage, current loop control system. The entire circuit includes a voltage reference,voltage amplifier, enabling dimming module, PWM comparator, current amplifier module,oscillator module, control logic circuit module.According to the performance requirements of the LED driver circuit, we use Cadencemain modules of the driver circuit designed for simulation tests. Under typical conditions(temperature of300K), PWM comparator accuracy of2mV, gain5V/2mV=2500, the outputvoltage of the system settling time of100s, when the supply voltage between2.0V to5.5Vsystem changes the output voltage is1.21428V to1.21455V voltage changes, voltagecoefficient of88ppm, with38dB power supply rejection ratio100kHz. The simulation resultsshow that, LED driver circuit designed in this paper reaches a predetermined designrequirements.