Back to results
US 5,668,866 AGranted
Apparatus for protecting a subscriber line interface circuit against overvoltages
AssigneeTelefonaktiebolaget LM Ericsson
InventorHans O. Eriksson
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeTelefonaktiebolaget LM Ericsson
InventorHans O. Eriksson
Estimating the term…
An apparatus interfaces with a subscriber line interface circuit (1) and protects the interface circuit (1) against overvoltages exceeding a supply voltage source supplied to the subscriber line interface circuit. The apparatus includes first and second diodes (DA1, DB1) having respective anodes connected to first and second input wires (A, B). The cathodes of the first and second diodes are connected to a positive terminal of the supply voltage source. The apparatus further includes third and fourth diodes (DA2, DB2) having cathodes connected the first and second input wires (A, B). The anodes of the third and fourth diodes are connected to a cathode of a thyristor (TAB). The anode of the thyristor, in turn, is connected to the positive terminal of the supply voltage source, and the gate the thyristor is connected to a negative terminal of the supply voltage source.
An apparatus for protecting a subscriber line interface circuit against overvoltages exceeding a supply voltage source supplied to the subscriber line interface circuit, wherein said overvoltages occur on first and second input wires which are connected to said interface circuit via respective first and second input terminals of said interface circuit, wherein resistors are connected in series with respective said input wires, wherein said first and second input terminals are connected to anodes of respective first and second diodes, and wherein cathodes of the first and second diodes are connected to a positive terminal of the supply voltage source, further wherein said first and second input terminals are also connected to cathodes of respective third and fourth diodes, wherein anodes of said third and fourth diodes are connected to a cathode of a thyristor, wherein an anode of the thyristor is connected to the positive terminal of the supply voltage source and a gate of said thyristor is connected to a negative terminal of said supply voltage source.
An apparatus for protecting a subscriber line interface circuit against overvoltages that exceed a supply voltage source supplied to said subscriber line interface circuit, wherein said overvoltages occur on first and second input wires which are connected to respective input terminals of a primary overvoltage protector, wherein resistors are connected in series with respective said input wires, wherein said primary overvoltage protector is connected in cascade to a secondary overvoltage protector and said secondary overvoltage protector is connected in cascade to a tertiary overvoltage protector, and said tertiary overvoltage protector is connected in cascade to the subscriber line interface circuit via first and second input terminals, wherein the secondary overvoltage protector is connected to apparatus earth, wherein said respective first and second input terminals of the subscriber line interface circuit are connected to anodes of respective first and second diodes and wherein cathodes of the first and second diodes are connected to a positive terminal of the supply voltage source, further wherein the tertiary overvoltage protector also includes a thyristor and third and a fourth diodes, wherein said respective input terminals of the subscriber line interface circuit are also connected to respective cathodes of said respective third and fourth diodes, wherein anodes of the third and fourth diodes are connected to a cathode of the thyristor, and wherein an anode of said thyristor is connected to the positive terminal of the supply voltage source and a gate of the thyristor is connected to a negative terminal of the supply voltage source.
Dependencies are inferred from the claim text.