Design Of CRM Voltage Mode APFC Controller XD7561

With booming development of electronic industry, electronic products and equipments have become more and more popular in everyday life. These products and equipments are mainly supplied by DC power. But traditional AC-DC technology is of low power factor, which resulted in series electrical energy waste and electrical web pollution. And for its wide input range and high power factor, APFC (Active Power Factor Correct) controller has found attractive in most applications.The paper is based on the project"Theoretical Research and Design of Key Technique for AC/DC convertor with BCD process"of Xidian University and focuses on the scheme, design and realization of APFC controller. The concept of power factor and harmonics distortion is described, then principle and control mode are presented and the steady-state analysis of boost voltage mode APFC system is detailed. Finally XD7561 is designed, according to its application, blocks as under voltage lock-out, zero current detector, over current protection, error.amplifier and a high precision current reference with piecewise curvature compensation are included. With very simple scheme, the chip has extremely good performance that its PF is up to 0.999, and THD is low to 0.047 with full load.The input current and voltage can be effectively synchronized the designed APFC controller chip, which dramatically optimizes THD. Based on 0.4μm 40V BCD process, the chip is simulated and taped out, and the test results satisfy requirements successfully.