AN702 vishay siliconix document number: 70576 www.vishay.com faxback 408-970-5600 1 efficient isdn power converters using the si9100
one of the latest technology revolutions, an integrated worldwide telecommunications network, will be accompanied by another advance in power conversion technology. the integrated services digital network (isdn) will allow different forms of information (voice, computer data, video, facsimile, etc.) to be transmitted over the telephone network. the international consultative committee for telephone and telegraph (ccitt) has proposed standards for the interfaces required to implement isdn. although the standards have yet to be formally adopted, telecommunications companies are moving ahead with pilot test programs, and semiconductor makers are developing chip sets to build isdn hardware. every network terminator (nt), signal regenerator (rg), and terminal equipment (te) unit used for the implementation of isdn will require a power converter. [1] a major requirement of these telecom applications (due to the need for emergency-mode operation from a high-impedance source) is high-efficiency energy conversion at fractional-watt power levels. minimization of parts count, another key factor for the design of these power converters, is sought to simultaneously achieve low cost and high reliability. bic/dmos integrated circuit technology is ideally suited for the power requirements of isdn. the analog and digital logic functions needed for pulse-width modulation can be implemented in cmos to minimize quiescent current to the controller. dmos transistors provide high-voltage power switching with both very low dynamic and gate drive losses. integration of the cmos controller on the dmos power device yields the best overall performance at the lowest cost and component count.
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