The impact of ISDN on Japan's telecommunications power system

The authors describe the state of ISDN (integrated services digital network) services in Japan and discuss issues concerning power supply systems suitable for the ISDN age. A distributed power supply system has been developed to solve the problems posed by centralized systems in telephone offices when ISDN systems are adopted. A compact, thin board-mounted DC-DC converter for a digital switch system has been developed. In addition, a small-size constant-current DC-DC converter has been developed for the metallic subscriber-loop system. A small-capacity uninterruptible power unit with back-up batteries, for use on subscriber's premises, has been developed for the optical-fiber subscriber loop systems. An extremely lightweight, high-voltage DC-DC converter for a communications satellite has also been developed.<
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