Vishay manufactures a broad range of components for mobile phone (cell phone) applications, including radio frequency (RF) control, audio control, visual display, and power management. Vishay components also enable the use of SIM cards, support USB connectivity between cell phones and peripherals, enable data exchange between IrDA-enabled or Bluetooth-enabled mobile phones and peripherals, and support other key functions.
Non-isolated point-of-load converters are generally used in intermediate bus architectures to step down the bus voltage. This multi-stage power conversion is widely implemented in telecom, computer, and consumer appliances. The POL modules or on-board POL circuits can be placed close to the payload, thereby adding flexibility to the design.
Today network subscriber linecards handle many different functions by means of subgroups on the main board or individual modules. One of the most important functions of the main board is to provide distributed power to the subgroups or modules and switch them on and off in order to provide overvoltage / overcurrent protection and filtering, as well as to switch signals correctly. In many cases, the central power supply is part of the main board. Several dc-to-dc converters generate the individual voltages, either directly in or close to the application module as a point of load solution. This is the case for DSLAM, routers, xDSL, Ethernet, optical access, and PoE. Individual protection of data lines is essential to the safe operation of linecards.
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.
For an xDSL network, each subscriber needs a so-called "Splitter" to divide the narrowband signals of the POTS (Plain Old Telephone Service) or ISDN (Integrated Services Digital Network) and the wideband xDSL signals. This is done by a combination of tight-tolerance low-pass and high-pass filters.
