Protection Circuit and Method
Apparatuses and methods for coupling a voltage supply input of an interface circuit of a communication device to a reference potential in response to at least one of an over-voltage and an over-current occurring in a communication line.
1 . An apparatus, comprising:
a detection circuit configured to detect an over-voltage on a conductive line; and
a control circuit configured to control an interface circuit to reduce a voltage on the conductive line in response to the over-voltage, wherein the interface circuit is configured to be coupled with a communication line.
2 . The apparatus of claim 1 , wherein the conductive line comprises a power supply line of the apparatus, the apparatus further comprising a transfer circuit coupled the communication line and configured to at least partially transfer to the power supply line at least one of the following: an over-voltage on the communication line and an over-current on the communication line.
3 . The apparatus of claim 2 , wherein the transfer circuit comprises a diode bridge.
4 . The apparatus of claim 2 , wherein the detection circuit and the interface circuit are each coupled with the power supply line.
5 . The apparatus of claim 1 , wherein the control circuit is configured to control the interface circuit to couple the conductive line to a reference potential in response to the over-voltage.
6 . The apparatus of claim 1 , further comprising a DC/DC converter coupled to the conductive line, wherein the control circuit is configured to control the DC/DC converter to reduce the voltage on the conductive line in response to the over-voltage.
7 . The apparatus of claim 1 , further comprising a switching element controlled by said control circuit and configured to selectively couple the conductive line to a reference potential.
8 . The apparatus of claim 1 , further comprising a capacitor coupled between the conductive line and a reference potential.
9 . An apparatus, comprising:
a plurality of interface circuits each coupled to a respective communication line;
a voltage supply line coupled with said plurality of interface circuits;
a plurality of transfer circuits, one of each transfer circuit being coupled to a respective one of the communication lines and configured to at least partially transfer an over-voltage on the respective communication line to the voltage supply line;
a detection circuit coupled to the voltage supply line and configured to detect an over-voltage on the voltage supply line; and
a control circuit coupled with said detection circuit and configured to control at least one of the interface circuits to couple the voltage supply line to a reference potential in response to the over-voltage on the voltage supply line.
10 . The apparatus of claim 9 , wherein each of the interface circuits comprises a subscriber line interface circuit.
11 . The apparatus of claim 9 , wherein each of the transfer circuits comprises a diode bridge.
12 . The communication device according to claim 9 , wherein at least one of the interface circuits comprises a switch element coupled between the voltage supply line and a reference voltage, a control input of the switch element configured to be controlled by the control circuit.
13 . The apparatus of claim 12 , wherein the switch element comprises a transistor.
14 . The communication device according to claim 9 , further comprising a positive temperature coefficient thermistor coupled in series with at least one of the communication lines.
15 . The apparatus of claim 9 , wherein apparatus is configured as a line card.
16 . The apparatus of claim 9 , further comprising a capacitor coupled between the voltage supply line and a reference potential.
17 . The apparatus of claim 9 , wherein the control circuit is configured to control less than all of the interface circuits to couple the voltage supply line to a reference potential in response to the over-voltage on the voltage supply line.
18 . A method, comprising:
transferring current from a first conductive line to a second conductive line in response to at least one of an over-voltage and an over-current occurring on the first conductive line;
detecting an over-voltage on the second conductive line, and
reducing a voltage on the second conductive line responsive to detecting the over-voltage on the second conductive line.
19 . The method of claim 18 , wherein the first conductive line is a communication line.
20 . The method of claim 18 , wherein reducing comprises coupling the second conductive line to a reference potential.
21 . The method of claim 18 , wherein reducing comprises controlling a DC/DC converter to reduce the voltage.
22 . A method, comprising coupling a voltage supply input of an interface circuit of a communication device to a reference potential in response to at least one of an over-voltage and an over-current occurring in a communication line.
23 . The method of claim 22 , wherein the reference potential is ground.
24 . The method of claim 22 , selecting the interface circuit from a plurality of interface circuits depending upon which of the plurality of interface circuits is inactive.
25 . The method of claim 22 , further comprising diverting current from the communication line to the voltage supply input in response to the at least one of the over-voltage and the over-current in the communication line.