Key power supplies from A to YAhe design of Switching Power Supplies has become one of the most crucial aspects of power electronics, partially in the explosive market for portable devices. Unfortunately, this seemingly simple mechanism is actually one of the most complex and under-estimated processes in Power Electronics. Switching power conversion involves several engineering disciplines: Semiconductor Physics, Thermal Management, Control Loop theory, Magnetics etc, and all these come into play eventually, in ways hard for non-experts to grasp.