xDSL Modem/Router Design is separated into two segments: Power and Peripheral. The Power Segment involves supplying hardware device power sources. The first step is to convert the working voltage to a usable range and stability by applying switching mode dc-to-dc Buck Converters with high efficiency and high current capability. Another voltage conversion is done for the the key power sources such as CPUs and DSPs. For the I/O parts and Memory Power, Low-Dropout Regulators or Linear Regulation is generally used as a solution because of their lower prices and simple circuitry. The Peripheral Segment can be regarded as a low-power segment. It includes USB Ports, External Connections, Wireless Transmission such as WLAN, and Control Lights. Some of these need similar functions such as ESD protection, current limiting, or load switching.