Protection of a telephone line against overvoltages

Patent metadata

Field	Value
Publication number	US-10148810-B2
Application number	US-201615045935-A
Country	US
Kind code	B2
Filing date	Feb 17, 2016
Priority date	Jul 13, 2015
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A structure protects a SLIC telephone line interface against overvoltages lower than a negative threshold or higher than a positive threshold. The structure includes at least one thyristor connected between each conductor of the telephone line and a reference potential. For all of the included thyristors, a metallization corresponding to the main electrode on the gate side is in contact, by its entire surface, with a corresponding semiconductor region. Furthermore, the gate of each thyristor is directly connected to a voltage source defining one of the thresholds.

First claim

The invention claimed is:

1. A structure for protecting a first line and a second line against overvoltages lower than a negative threshold or higher than a positive threshold, comprising:
at least one thyristor connected between each of the first and second lines and a reference potential;
wherein, for all thyristors:
a metallization corresponding to an electrode on a gate side, wherein that metallization is in contact, by its entire surface, with a surface of a corresponding semiconductor region; and
the gate is directly connected to a voltage source providing a DC voltage defining one of said negative and positive thresholds.

2. The structure of claim 1 , wherein the positive threshold is zero, comprising:
each of the first and second lines is coupled to the anode of a diode and to the cathode of a cathode-gate thyristor, and cathodes of the diodes and the anodes of the thyristors are coupled to the reference potential;
a common negative DC voltage source connected to the two gates of the cathode-gate thyristors.

3. The structure of claim 2 , wherein the cathode-gate thyristors and the diodes are formed in a same monolithic component.

4. The structure of claim 1 , wherein:
each of the first and second lines is connected to the cathode of a cathode-gate thyristor and to the anode of an anode-gate thyristor, the anodes of the cathode-gate thyristors and the cathodes of the anode-gate thyristors being coupled to the reference potential;
the gates of the cathode-gate thyristors are directly connected to a common negative DC voltage source defining the negative threshold; and
the gates of the anode-gate thyristors are directly connected to a common positive DC voltage source defining the positive threshold.

5. The structure of claim 4 , wherein all thyristors are formed in a same monolithic component.

6. The structure of claim 1 , wherein at least one of the voltage sources is a power supply source of a Subscriber Line Interface Circuit (SLIC) for the first and second lines.

7. The structure of claim 1 , wherein at least one of the voltage sources comprises at least one battery.

8. A structure for protecting a first line and a second line against overvoltages lower than a negative threshold or higher than a positive threshold, comprising:
at least one thyristor connected between each of the first and second lines and a reference potential;
wherein:
all thyristors have no emitter short circuits; and
all thyristors have a semiconductor gate region maintained at one of a negative and positive DC potential by a gate electrode.

9. The structure of claim 8 , wherein the positive threshold is zero, comprising:
each of the first and second lines is coupled to the anode of a diode and to the cathode of a cathode-gate thyristor, and cathodes of the diodes and the anodes of the thyristors are coupled to the reference potential;
a common negative potential is maintained at the two gates of the cathode-gate thyristors.

10. The structure of claim 8 , wherein the positive threshold is zero, comprising:
each of the first and second lines is coupled to the anode of a diode and to the cathode of a cathode-gate thyristor, and cathodes of the diodes and the anodes of the thyristors are coupled to the reference potential;
a common negative potential is maintained at the two gates of the cathode-gate thyristors.

11. The structure of claim 8 , wherein the at least one thyristor is:
conductive when the voltage between one of the first and second line and the reference potential is greater than one of the positive DC potential and negative DC potential; and
non-conductive when the voltage between one of the first and second line and the reference potential is less than one of the positive DC potential and negative DC potential.

Assignees

• St Microelectronics Tours Sas

Inventors

• Simonnet Jean-Michel
• Ballon Christian

Classifications

• H04M1/745 Primary

  Protection devices or circuits for voltages surges on the line · CPC title

• H04M3/005

  Interface circuits for subscriber lines (current supply H04M19/00 and subgroups; supervisory, monitoring or testing arrangements H04M3/22 and subgroups; in key telephone systems H04M9/006) · CPC title

• H04M2201/80

  line protection circuits such as current or overvoltage protection circuits · CPC title

• H02H9/043

  Protection of over-voltage protection device by short-circuiting · CPC title

• H02H9/041 Primary

  using a short-circuiting device · CPC title