voltage between selected limits, limiting schutzschaltung and their monolitsche integration

摘要

The present invention relates to a circuit for protecting lines such as telephone lines against positive or negative overvoltages with given respective minimum values (+V1 and -V2), comprising between a common point (C), on the one hand, and a first line (A), a second line (B) and earth (M), on the other hand, first, second and third protection elements consisting respectively of a diode (D1, D2, D3) in antiparallel with a thyristor (T1, T2, T3) whose anode is connected to the common point and whose gate receives a bias signal, the first and second thyristors being cathode-gated and the third (T1) anode-gated. Each of the first and second thyristors is associated with a transistor (TR2, TR3), the emitter of each transistor being connected to the gate of the corresponding thyristor and the collector of each transistor being connected to a second common point (D) connected up to the gate of the third thyristor. …IMAGE…