Various methods and apparatuses for a surge protection scheme
View Patent ↗In general, various methods, apparatuses, and systems for a surge protection circuit for a Public Switched Telephone Network (PSTN) are disclosed. The surge protection circuit includes a first voltage protection device coupled to a first wire of the PSTN. A voltage protection device conducts when voltage applied across the voltage protection device at least meets a set voltage threshold. The surge protection circuit includes a second voltage protection device coupled to a second wire of the PSTN. The second voltage protection device is coupled to the first voltage protection device in series. The surge protection circuit includes a voltage divider device to cause a voltage applied differentially across the first wire and second wire to divide evenly across the first voltage protection device and the second voltage protection device.
1. An apparatus, comprising:
a digital subscriber line modem comprising a surge protection circuit having a first voltage protection device coupled to a first TIP wire of a Public Switched Telephone Network (PSTN), a voltage protection device to conduct when voltage applied across the voltage protection device at least meets a set voltage threshold, a second voltage protection device coupled to a first RING wire of the PSTN, the second voltage protection device coupling to the first voltage protection device, and a third voltage protection device coupled to the first voltage protection device and second voltage protection device in a wye configuration; and
an external power supply, wherein the modem is connected to the external power supply to power the modem using a cable comprising a modem side two pin connector, wherein the cable further comprises:
a positive voltage conductor having a first end coupled to a first one of the two pins of the modem side two pin connector, wherein the positive voltage conductor has a second end coupled to a first conductor in the power supply;
a neutral conductor having a first end coupled to a second one of the two pins of the modem side two pin connector, wherein the neutral conductor has a second end coupled to a second conductor in the power supply; and
an earth conductor having a first end coupled to the neutral conductor and the second one of the two pins of the modem side two pin connector, wherein the earth conductor has a second end coupled to a third conductor in the power supply being different than the second conductor in the power supply, wherein the second end of the earth conductor is further connected to earth ground through the power supply to provide a return path for surge return current.
2. The apparatus recited in claim 1 , further comprising a voltage divider device configured to provide a voltage applied differentially across the first TIP wire and first RING wire to divide evenly across the first voltage protection device and the second voltage protection device, wherein the voltage divider device comprises a series coupling of a first resistor and a second resistor connected in parallel to the first voltage protection device and the second voltage protection device.
3. The apparatus recited in claim 2 , wherein the third voltage protection device is connected in parallel to a third resistor.
4. A method, comprising:
applying a voltage to a surge protection circuit of a digital subscriber line modem through a TIP and/or RING wire of a Public Switched Telephone Network (PSTN), wherein the surge protection circuit having a first voltage protection device being coupled to a second voltage protection device and a third voltage protection device being coupled to the first and the second voltage protection devices in a wye configuration;
producing a surge current when the voltage applied at least meets a set voltage threshold, wherein the surge current flows from the digital subscriber line modem to a cable through a first pin of a modem side two-pin connector of the cable; and
providing a return path for the surge current to be grounded without allowing the surge current to loop back to a power supply providing the applied voltage, wherein the return path includes a earth conductor, of the cable, having a first end being coupled to the first pin of the modem side two-pin connector of the cable and having a second end being grounded through the power supply, wherein the return path prevents the surge current from entering a neutral conductor through the first pin of the modem side two-pin connector, the neutral conductor having a first end being coupled to the first pin of the modem side two-pin connector of the cable and having a second end coupled to a first conductor in the power supply, or a positive voltage conductor through the second pin of the modem side two-pin connector, the positive voltage conductor having a first end coupled to a second pin of the modem side two-pin connector and a second end coupled to a second conductor in the power supply.