Switching Power Supplies A - Z, 2nd Edition

Chapter 3

Off-Line Converter Design and Magnetics

First, the transformer-based flyback topology is introduced and it is shown how it can be mapped into equivalent inductor-based Buck-Boost models for easy analysis and design. Flyback zener clamp design is discussed here, and the importance of reducing both Primary-side and secondary-side leakage inductances is highlighted. Concepts like skin depth are introduced, and a quick-lookup chart is provided for designing the flyback transformer’s windings, keeping in mind the target current density (in cmil/A or A/m²). Temperature rise of commonly used cores is also discussed. Next, the Forward converter is introduced and the designs of both its output choke and transformer are discussed in detail. This ...