In the following article you will be provided with a 20W, 5V at 4A, step-down regulator which is developed using
LM2577 “Simple Switcher” in a forward converter topology. This
topology can easily provide galvanic isolation between input and output.
In the depth of the article there are sections describe the design procedures which begins with the transformer design, the output filter and snubber circuit design. As you can see in the diagram,
Diodes (Dr and Df are 5A, 30V Scottky diodes which is the same type
used for Dc). The regulator’s stability are optimized by the Rc and Cc compensation network and provides a soft-start function for a well-controlled power-up.
Read completely about the design procedures of 5V 4A Step-Down Regulator Circuit in Forward Converter Topology in this circuit application article here (source: national.com).