Modern AC/DC and DC/DC converters are designed to provide efficient power conversion to deliver a controlled, safe and well-regulated DC power supply for a variety of electronic instruments, devices and systems. It’s not all too long ago that a transformer, rectifier and linear regulator was the main technology in power conversion, but just as the LED is slowly replacing the light bulb, so is the DC/DC converter gradually edging out the linear regulator and the primary-side switching controller is replacing the simple 50Hz mains transformer. In the past decade there has been of immense technical progress the development of switching regulators to allow the benefits of new circuits, components, and materials that previously simply did not exist before. This progress has made it possible to increase the performance and to improve the thermal behavior, while simultaneously substantially reducing the size, weight and cost of power supplies. Consequently, switching regulators are used today in large numbers and are the standard technology in both DC/DC and AC/DC power conversion.