Power feed circuit providing both on-hook and off-hook power for telephone subscriber loop

• US 6,157,716 A
• Filed: 05/08/1998
• Issued: 12/05/2000
• Est. Priority Date: 05/08/1998
• Status: Expired due to Fees

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: Verizon Communications Inc.
• Inventors: Ortel, William C. G.
• Primary Examiner(s): WOO, STELLA L
• Application Number:
  US09/075,094
• Time in Patent Office: 942 Days
• Field of Search: 379/413, 379/322, 379/323, 379/324, 379/399
• US Class Current: 379/413
• CPC Class Codes: H04M 19/001 Current supply source at the exchanger providing current to substations

Abstract

A power feed circuit provides power for a telephone subscriber loop connected to a unit of terminal equipment. The power feed circuit includes a first current supply circuit for supplying power to the subscriber loop when the unit of terminal equipment is in an on-hook condition and when the unit of terminal equipment is in an off-hook condition, and a second current supply circuit for supplying power to the subscriber loop only when the unit of terminal equipment is in the off-hook condition. Each current supply circuit includes a respective battery, transistor and bias network. The first current supply circuit is connected to the subscriber loop via a diode which is reverse-biased when the unit of terminal equipment is in the on-hook condition. The power feed circuit may be usefully applied in an Optical Network Unit (ONU) of a "fiber-in-the-loop" telephone system or in a Subscriber-Cable Interface Unit (SCIU) of a cable telephony system.

Claims

1. A power feed circuit for a telephone subscriber loop, the loop connected to a unit of terminal equipment, the unit of terminal equipment being switchable between an on-hook condition and an off-hook condition;

the power feed circuit comprising;

a first current supply circuit for supplying power to said subscriber loop when said unit of terminal equipment is in said on-hook condition and when said unit of terminal equipment is in said off-hook condition; and

a second current supply circuit for supplying power to said subscriber loop only when said unit of terminal equipment is in said off-hook condition.

2. A power feed circuit according to claim 1, wherein said first current supply circuit includes a first battery and said second current supply circuit includes a second battery.

3. A power feed circuit according to claim 1, wherein said first and second current supply circuits are connected in parallel to said subscriber loop.

4. A power feed circuit according to claim 3, wherein said second current supply circuit is connected to said subscriber loop via a diode, and said diode is reverse-biased when said unit of terminal equipment is in said on-hook condition.

5. A power feed circuit according to claim 1, further comprising a first loop terminal and a second loop terminal, said first and second loop terminals for connecting said power feed circuit to said subscriber loop;

wherein said first current supply circuit includes;

a first battery having a positive terminal and a negative terminal, said positive terminal connected to said first loop terminal;

a first transistor having a collector terminal, an emitter terminal and a base terminal;

a diode connected between said second loop terminal of the power feed circuit and said collector terminal of said first transistor, with said diode having a polarity for conducting current only in the direction from said second loop terminal to said collector terminal;

a first emitter resistor connected between said emitter terminal of said first transistor and said negative terminal of said first battery;

a first bias resistor connected between said positive terminal of said first battery and said base terminal of said first transistor; and

a second bias resistor connected between said negative terminal of said first battery and said base terminal of said first transistor;

and wherein said second current supply circuit includes;

a second battery having a positive terminal and a negative terminal, said positive terminal of said second battery connected to said first loop terminal;

a second transistor having a collector terminal, an emitter terminal and a base terminal, said collector terminal of said second transistor connected to said second loop terminal of the power feed circuit;

a second emitter resistor connected between said emitter terminal of said second transistor and said negative terminal of said second battery;

a third bias resistor connected between said positive terminal of said second battery and said base terminal of said second transistor; and

a fourth bias resistor connected between said negative terminal of said second battery and said base terminal of said second transistor.

6. A power feed circuit according to claim 5, wherein said first battery has a nominal voltage rating of 12 V and said second battery has a nominal voltage rating of 24 V.

7. A power feed circuit for a telephone subscriber loop, the loop connected to a unit of terminal equipment, the unit of terminal equipment being switchable between an on-hook condition and an off-hook condition;

the power feed circuit comprising;

a first current supply means for supplying power to said subscriber loop when said unit of terminal equipment is in said on-hook condition and when said unit of terminal equipment is in said off-hook condition; and

a second current supply means for supplying power to said subscriber loop only when said unit of terminal equipment is in said off-hook condition.

8. A power feed circuit according to claim 7, wherein said first current supply means includes a first battery and said second current supply circuit includes a second battery.

9. A power feed circuit according to claim 7, wherein said first and second current supply means are connected in parallel to said subscriber loop.

10. A power feed circuit according to claim 9, wherein said second current supply means is connected to said subscriber loop via a diode, and said diode is reverse-biased when said unit of terminal equipment is in said on-hook condition.

11. A power feed circuit according to claim 7, further comprising a first loop terminal and a second loop terminal, said first and second loop terminals for connecting said power feed circuit to said subscriber loop;

wherein said first current supply means includes;

a first battery having a position terminal and a negative terminal, said positive terminal connected to said first loop terminal;

a first transistor having a collector terminal, an emitter terminal and a base terminal;

a diode connected between said second loop terminal of the power feed circuit and said collector terminal of said first transistor, with said diode having a polarity for conducting current only in the direction from said second loop terminal to said collector terminal;

a first emitter resistor connected between said emitter terminal of said first transistor and said negative terminal of said first battery;

a first bias resistor connected between said positive terminal of said first battery and said base terminal of said first transistor; and

a second bias resistor connected between said negative terminal of said first battery and said base terminal of said first transistor;

and wherein said second current supply means includes;

a second battery having a positive terminal and a negative terminal, said positive terminal of said second battery connected to said first loop terminal;

a second transistor having a collector terminal, an emitter terminal and a base terminal, said collector terminal of said second transistor connected to said second loop terminal of the power feed circuit;

a second emitter resistor connected between said emitter terminal of said second transistor and said negative terminal of said second battery;

a third bias resistor connected between said positive terminal of said second battery and said base terminal of said second transistor; and

a fourth bias resistor connected between said negative terminal of said second battery and said base terminal of said second transistor.

12. A power feed circuit according to claim 11, wherein said first battery has a nominal voltage rating of 12 V and said second battery has a nominal voltage rating of 24 V.

13. A method of feeding power to a telephone subscriber loop, the loop connected to a unit of terminal equipment, the terminal equipment being switchable between an on-hook condition and an off-hook condition;

the method comprising;

supplying power to said subscriber loop with a first current supply circuit when said unit of terminal equipment is in an on-hook condition and when said unit of terminal equipment is in said off-hook condition; and

supplying power to said subscriber loop with a second current supply circuit only when said unit of terminal equipment is in said off-hook condition.