Stmicroelectronics S.a.

Sgs-thomson Microelectronics S.a.

Stmicroelectronics(tours) Sas

André Bremond

Philippe Merceron

Cédric Appere

Robert Pezzani

François Dupont

Fabrice Guitton

Christian Ballon

Albert Senes

A structure for protecting a circuit connected to first and second rails of a telephone connection against overvoltages, including: first and second diodes in anti-series between the first and second rails; a first capacitor in parallel with a first resistor between a first node common to the first and second diodes and a low voltage reference node; and a protection element capable of removing fast overvoltages between any of the rails and the low reference voltage node when these overvoltages exceed a first threshold associated with the voltage of the first node.

Anti-lightning protection for telephone connection

A circuit for protecting electronic equipment intended to be connected to at least one first conductor of a communication line, including, between this first conductor and a second conductor of the line or the ground to which is connected the equipment to be protected, at least one first branch including, in series, a first capacitive element and a first voltage-threshold triggering element, a first resistive element being connected in parallel with the first capacitive element.

Protection of a communication line

A high-frequency coupler for extracting a secondary signal representative of a main signal carried by a conductive line, including two series-coupled, respectively high-pass and low-pass, filters, and the input of which is intended to be connected to said line while its output is intended to provide the secondary signal, the filters being sized so that the sum of their respective attenuations is substantially constant over the coupler passband, and so that their respective cut-off frequencies are in said passband.

High-frequency coupler

An interface circuit including a galvanic isolation barrier between a transmission line and a user equipment, and a detector for detecting, independently from a transmission, the idle or busy state of the line.

Line take-up detection circuit

A series device for protection against a heating of aparallel protection element of an equipment of a telephone line, including a bi-directional cut-off element, of normally on state and placed in series with the parallel protection element, a temperature detection element, and a switching element adapted to turning off the cut-off element when the temperature detected by the detection element exceeds a predetermined threshold.

Circuit for protection against heating of a protection element of equipment

The present invention relates to a system for protecting against overloads in a telephone system. The telephone system includes a telephone exchange, a ringing device and an interface, coupled to receive input signals on subscriber lines. The input signals are forwarded to either the telephone exchange or the ringing device depending upon the operating mode of the telephone system. The telephone line supplies a signal indicating the operating mode. A single protection device is coupled between the input of the subscriber lines and the interface. The protection device is controlled by the operating mode signal, and includes logic for protecting both the ringing device and the telephone exchange.

Protection against overvoltages of an interface of telephone lines

An overvoltage protection circuit for a load having a determined resistance value is connected to a supply line with a predetermined polarity. An overvoltage detector is connected across the line. A first switch, normally on, is located in series with a conductor of the line and is controlled (i.e. switched to the off state) by the detector. A second switch, located in series with a resistance having the same determined value R, is disposed between the line conductors and is controlled by the detector in a complementary manner to the first switch.

Series protection circuit

A protection device against overvoltages liable to occur between two supply terminals (A, B) comprises between the terminals, on the one hand, a thyristor (Th) and, on the other hand, first and second zener diodes in series. The anode of the first diode (D1) is connected to the cathode of the thyristor and the cathode of the second diode (D2) is connected to the anode of the thyristor, and a third zener diode (D3) is placed between the thyristor gate and the junction (10) of the first and second diodes. The third diode has an avalanche voltage higher than that of the first diode.

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Veretz, France

André Bremond