SMPS design: Switch mode power supply based on Dual Switch Flyback Topology

By Aries Huang, Fairchild Semiconductor

Abstract: Power-electronics engineers designing switched mode power supplies (SMPS) are faced with the challenges of limited space, the need to meet worldwide energy regulations, and ease of design. Dual switch QR flyback topology and secondary synchronous rectification is the ideal solution to meet future energey regulation - providing good overall efficiency, managing low power loss at light load, while providing ease of design. The validity of the proposed topology is verified with a 90W prototype power supply.

Introduction: Because of the increasing concern for the environmental issues, the design of power supplies for high efficiency and low standby power consumption keeps gaining attention in these years. Soft-switching or resonant conversion topologies are utilized in recent years to meet high efficiency challenge. However, future challenge for low power consumption, low cost, easy design and manufacturing poses a huge challenge to current resonant topologies. The purpose of this article is to illustrate the operation theory and benefit of a new proposed topology: two-switch quasi-resonant (QR) flyback converter and demonstrate a 90W power design which fulfills the requirement of high-efficiency (> 90%) and slim form factor ( 60mm x 95 mm x 16.5mm) while meeting 2013 ErP power saving request ( <0.5W under 0.2...