Design Of A Boost Active Power Factor Correction Controller XD8537 For Driving LED

In the lighting application, LED (Light Emitting Diode), with many advantages of high luminous efficiency, longevity, high brightness, energy-saving, environmental friendly and durable, is becoming a new lighting source and is being widely applied. However, the use of conventional switch mode power supply, which is used to drive LED, causes the problem that more and more harmonics have been brought to the power system, leading to a heavier harmonic pollution to the electricity network. Thus, it affects the quality of power supply and the security of users. Active power factor correction (APFC) technology is a valid method to improve the power factor of electronic products, reduce electric pollution and harmonic interference. Therefore, APFC technology has emphasized in the research in the promotion of"green electricity network"and"green lighting"today.Based on the project of"Research on Boost APFC Controller"in the Institute of Electronic CAD in Xidian University, a boost APFC controller XD8537 for driving LED is designed. Firstly, the significance of the power factor correction technology and its development status are proposed in the paper. Secondly, the basic topologies of APFC are described, as well as control methods and operate modes. Thirdly, based on the analysis above, the system design, circuit design and simulation have been completed. In view of the disadvantage of the traditional power factor correction chip in slow transient response, a novel high-slew-rate transconductance error amplifier which can safely and promptly deal with the circuit fault, short or the suddenly change of the load is designed. Besides, a variable on-time control method is employed to further optimize the total harmonic distortion (THD).The APFC controller XD8537 designed in the paper is based on 0.4μm 40V BCD process and operates in the critical conduction mode by voltage mode controlling. So it has the characteristics of simple structure, small size and high power factor. The simulation results by HSPICE show that the chip realizes the function of power factor correction (PFC) perfectly, and all the simulation parameters meet the specification well.