A Boost LED Driver Chip Design

With the characteristics of energy efficient, green and clean,the LED which is a new kind of light source is beginning deepened people’s lives.In general lighting,incandescent has low energy utilization and energy-saving lamp is made of mercury which would cause environmental pollution,so LED will replace both and become the subject of lighting products.In this thesis, a power management circuit for LED driver are designed based on the step-up DC-DC converter used a peak current-mode PWM modulation,the typical operated frequency of 1.7MHz,the input voltage of 2.7V~5.5V,the maximum output voltage up to 20 V,which can drive six series power LEDs with threshold voltage of3 V.Due to reliability of the chip,in addition to functional modules, this issue also design overtemperature protection circuit,undervoltage protection circuit and output overvoltage protection circuit,making the chip proper function and driving LED load in a common working conditions.PWM modulation technology with low cost design, has a high conversion efficiency when drives power LED.Chip clock frequency tuning module that operates at clock frequencies can be achieved adjusted within the range of1.48MHz~1.96 MHz.In this paper, the adaptive dynamic slope compensation technology,can achieve a stable output voltage of the switching duty cycle from 50% to94%.This paper describes the LED applications, recent market development and research trends at home and abroad.The design parameters and requirements of this boost converter circuit are given and this issue also describes the basic principle of LED drivers and switching power circuits.According to the design parameters,this paper gives overall design of the boost LED driver IC including bandgap reference,oscillator and overtemperature protection circuit and gives simulation results and describes its structure in detail.Finally,the whole circuit are simulated for dimming function and efficiency with different loads and the results are agree with design expectations.