A Surge Protective Device with Dual Protection Levels for On-Hook and Off-Hook Operating Voltages in Telephone Networks

초록

Telecommunications facilities with the advance of highly information-oriented society require a higher transmission rate, LSI and VLSI circuits based on semiconductor technologies are widely used in communication devices. Modern microelectronic circuits may susceptible to damage by lightning surges. Therefore, the protection of electronic circuits from lightning surges is highly interested. Application of surge protective devices(SPDs) are to protect the communication facilities from lightning surges. The operating characteristics of the telephone network are divided into the on-hook state and the off-hook state. A subscriber protector is normally installed telecommunication lines, but it limit the incoming lightning surges to the protection level of the on-hook state. Thus the protection of telephone from overvoltages in the off-hook state is not achieved. In this paper, in order to solve the point at issue, the hybrid surge protective circuit of protecting the telephone from overvoltages in off-hook and on-hook states was designed. The operating characteristics of the proposed surge protective circuit were experimentally investigated and analyzed.