This document describes a power supply reference board designed for powering digital applications, such as CPUs, FPGAs, memories, etc. The main purpose of the board is to illustrate the basic principles used for the design of the power supply and to give designers a usable prototype for testing and use. The document also discusses the trend in recent years in the supplying of power to MCUs, CPUs, memories, FPGAs, etc., and the need for different voltage levels for different devices in one platform.