The Design Of A High Performance LED Driver IC With Fly-back Mode

The development of lighting will keep pace with the development of the times. The energy saving and environmental protection, which is two major issues in the world today, points out the development direction of the illumination. With high light efficiency and pollution-free characteristics, LED has a good prospect for development. However, unlike the incandescent lamp, the LED Lamp demand a high performance driver. The research and development of LED driver directly determines the competitiveness of merchants in the lighting market.Based on the above issues, to conform to the trend of the times, this paper introduces a design of a high performance LED power driver chip. The input voltage of the chip is 85V~265V, which is a wide range. At the same time, the application is very convenient because of the AC input voltage. The chip which has a off-line output, improves the safety when it is used. The main function of the chip is to achieve a constant output current and power factor correction. By sampling the current of primary side, the chip can give constant current output and has the function of PFC at the same time. The control loop is simple, which cut down the cost. Output current is constant and the power factor is above 0.95.In the process, through the analysis of the common LED driver and switching power supply topology, we determine the application circuit of the chip. Analyzing circuit control mode, overall structure of the chip is determined. Based on the above work, began to design core sub-modules. In this paper, a detailed analysis of the following modules: the reference voltage circuit, undervoltage lockout circuit and bandgap voltage reference, to provide reference and protection of these modules for the chip.Next, the paper gives simulation verification of the above several sub modules and then gives simulation verification of the chip. The chip can achieve the anticipant function.