Power feed for Ethernet telephones via Ethernet link

• US 6,115,468 A
• Filed: 03/26/1998
• Issued: 09/05/2000
• Est. Priority Date: 03/26/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: De Nicolo, Maurilio Tazio
• Primary Examiner(s): Hudspeth, David R.
• Assistant Examiner(s): Chawan, Vijay B
• Application Number:
  US09/048,922
• Time in Patent Office: 894 Days
• Field of Search: 379/413, 379/412, 379/900, 379/324, 375/285, 375/257, 375/258
• US Class Current: 379/413
• CPC Class Codes: H04B 2203/5437 Wired telephone
• CPC Class Codes: H04B 2203/547 via DC power distribution
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/548 the power on the line being DC arrangements for feeding power H04L12/10; extracting feeding power from signals H04L25/02
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: Y10S 379/90 Internet, e.g. Internet phone, webphone, internet-based telephony

Abstract

An Ethernet device power transmission system includes an input transformer, an output transformer and a pair of twisted pair conductors. The input transformer includes a pair of primaries for connection to a source of Ethernet data. The input transformer also includes a pair of secondaries, each having a center-tap. A first twisted pair conductor is connected across the first secondary, a second twisted pair conductor is connected across the second secondary and a DC-bias is provided between the respective center taps of the first and second secondaries. At the local end, the output transformer includes a first and second center-tapped primary and a first and second secondary for connection to the load device. The first and second primary center taps are connected to a power processor for extraction of DC power.

Claims

1. A power feed system for Ethernet telephones, said system comprising:

a first transformer including a first primary, a second primary, a first secondary with a first center-tap and a second secondary with a second center-tap, said first primary for coupling to a first pair of conductors, said second primary for coupling to a second pair of conductors;

a second transformer including a first primary with a first center-tap, a second primary with a second center-tap, a first secondary and a second secondary, said first and second secondaries for coupling to an Ethernet telephone;

an Ethernet link including a third pair of conductors is and a fourth pair of conductors, said third pair of conductors connecting said first secondary of said first transformer with said first primary of said second transformer and said fourth pair of conductors connecting said second secondary of said first transformer with said second primary of said second transformer;

a direct current power supply having a first output potential on a first line and a second output potential different from said first output potential on a second line, said first line connected to said first center-tap of said first transformer and said second line connected to said second center-tap of said first transformer;

a first potential input of an Ethernet telephone coupled to said first center-tap of said second transformer; and

a second potential input of an Ethernet telephone coupled to said second center-tap of said second transformer.

2. A power feed system for Ethernet telephones according to claim 1, wherein said third pair of conductors is a twisted pair.

3. A power feed system for Ethernet telephones according to claim 2, wherein said fourth pair of conductors is a twisted pair.

4. A power feed system for Ethernet telephones according to claim 3, wherein said first pair of conductors is a twisted pair.

5. A power feed system for Ethernet telephones according to claim 4, wherein said second pair of conductors is a twisted pair.

6. A system for supplying DC power to a remote device, said system comprising:

a first transformer including a first primary, a second primary, a first secondary with a first center-tap and a second secondary with a second center-tap, said first primary for coupling to a first pair of conductors, said second primary for coupling to a second pair of conductors;

a second transformer including a first primary with a first center-tap, a second primary with a second center-tap, a first secondary and a second secondary, said first and second secondaries for coupling to the remote device;

an Ethernet link including a third pair of conductors and a fourth pair of conductors, said third pair of conductors connecting said first secondary of said first transformer with said first primary of said second transformer and said fourth pair of conductors connecting said second secondary of said first transformer with said second primary of said second transformer;

a direct current power supply having a first output potential on a first line and a second output potential different from said first output potential on a second line, said first line connected to said first center-tap of said first transformer and said second line connected to said second center-tap of said first transformer;

a first potential input of the remote device coupled to said first center-tap of said second transformer; and

a second potential input of the remote device coupled to said second center-tap of said second transformer.

7. A system according to claim 6, wherein said third pair of conductors is a twisted pair.

8. A system according to claim 7, wherein said fourth pair of conductors is a twisted pair.

9. A system according to claim 8, wherein said first pair of conductors is a twisted pair.

10. A system according to claim 9, wherein said second pair of conductors is a twisted pair.

11. A system for transmitting data and a DC signal simultaneously between a first device and a second device, said system comprising:

a first transformer including a first primary, a second primary, a first secondary with a first center-tap and a second secondary with a second center-tap, said first primary for coupling to a first pair of conductors over which a first data signal is to be communicated with the first device, said second primary for coupling to a second pair of conductors over which a second data signal is to be communicated with the first device;

a second transformer including a first primary with a first center-tap, a second primary with a second center-tap, a first secondary and a second secondary, said secondary for coupling to a third pair of conductors over which said first data signal is to be communicated with the second device, and said second secondary for coupling to a fourth pair of first conductors over which said second data signal is to be communicated with the second device;

a link including a fifth pair of conductors and a sixth pair of conductors, said fifth pair of conductors connecting said first secondary of said first transformer with said first primary of said second transformer and said sixth pair of conductors connecting said second secondary of said first transformer with said second primary of said second transformer;

a direct current power supply associated with the first device having a first output potential on a first line and a second output potential different from said first output potential on a second line, said first line connected to said first center-tap of said first transformer and said second line connected to said second center-tap of said first transformer;

a first potential input of the second device coupled to said first center-tap of said second transformer; and

a second potential input of the second device coupled to said second center-tap of said second transformer.

12. A method for supplying a DC power connection and a bi-directional data connection to a remote device, said bi-directional data connection including a first data signal and a second data signal, said method comprising:

transmitting the first data signal to a first primary winding of a first transformer;

receiving the second data signal from a second primary winding of said first transformer;

transmitting the first data signal from a first secondary winding of said first transformer to a first primary winding of a second transformer;

transmitting the second data signal from a second primary winding of said second transformer to a second secondary winding of said first transformer;

transmitting the first data signal to the device over a first secondary winding of said second transformer;

receiving the second data signal from the device over a second secondary winding of said second transformer;

applying a DC signal between a center-tap of said first secondary winding of said first transformer and a center-tap of said second secondary winding of said first transformer;

extracting a DC signal from a center-tap of said first primary winding of said second transformer and a center-tap of said second primary winding of said second transformer; and

applying said DC signal to the remote device.

13. A power feed system for Ethernet telephones, said system comprising:

first coupling means for coupling a first conductor of a first pair of conductors to a first winding of a first transformer;

second coupling means for coupling a second conductor of said first pair of conductors to a second winding of said first transformer;

third coupling means for coupling a first conductor of a second pair of conductors to a first winding of a second transformer;

fourth coupling means for coupling a second conductor of said second pair of conductors to a second winding of said second transformer;

fifth coupling means for coupling a first and second conductor, respectively, of an Ethernet telephone to said first and second conductor of said second pair of conductors;

a first and second center-tapped winding disposed in said first transformer, each said winding having a first conductor, a second conductor and a center-tap conductor;

a first and second center-tapped winding disposed in said second transformer, each said winding having a first conductor, a second conductor and a center-tap conductor;

means for connecting said first conductor of said first center-tapped winding of said first transformer to said first conductor of said second center-tapped winding of said second transformer;

means for connecting said second conductor of said first center-tapped winding of said first transformer to said second conductor of said second center-tapped winding of said second transformer;

means for applying a power signal to said first center-tap conductor and said second center-tap conductor of said first transformer;

means for extracting a power signal from said first center-tap conductor and said second center-tap conductor of said second transformer and for applying said extracted power signal to said Ethernet telephone.

14. A system for supplying DC power to a remote device, said system comprising:

first coupling means for coupling a first conductor of a first pair of conductors to a first winding of a first transformer;

second coupling means for coupling a second conductor of said first pair of conductors to a second winding of said first transformer;

third coupling means for coupling a first conductor of a second pair of conductors to a first winding of a second transformer;

fourth coupling means for coupling a second conductor of said second pair of conductors to a second winding of said second trans former;

fifth coupling means for coupling a first and second conductor, respectively, of the remote device to said first and second conductor of said second pair of conductors;

a first and second center-tapped winding disposed in said first transformer, each said winding having a first conductor, a second conductor and a center-tap conductor;

a first and second center-tapped winding disposed in said second transformer, each said winding having a first conductor, a second conductor and a center-tap conductor;

means for connecting said first conductor of said first center-tapped winding of said first transformer to said first conductor of said second center-tapped winding of said second transformer;

means for connecting said second conductor of said first center-tapped winding of said first transformer to said second conductor of said second center-tapped winding of said second transformer;

means for applying a power signal to said first center-tapped conductor and said second center-tapped conductor of said first transformer;

means for extracting a power signal from said first center-tap conductor and said second center-tap conductor of said second transformer and for applying said extracted power signal to the remote device.

15. A method for supplying DC power to a remote device over a 4-wire Ethernet connection having a first twisted pair of conductors for transmission of data packets from said remote device and a second twisted pair of conductors for reception of data packets at said remote device, the method comprising:

applying a first polarity of the DC power to a center tap of a first transformer winding connected across a distal end of the first twisted pair of conductors;

applying a second polarity of the DC power to a center tap of a second transformer winding connected across a distal end of the second twisted pair of conductors;

extracting said first polarity from a center tap of a third transformer winding connected across a proximal end of the first twisted pair of conductors; and

extracting said second polarity from a center tap of a fourth transformer winding connected across a proximal end of the second twisted pair of conductors.

16. A system for supplying DC power to a remote device over a 4-wire Ethernet connection having a first twisted pair of conductors for transmission of data packets from said remote device and a second twisted pair of conductors for reception of data packets at said remote device, the system comprising:

means for applying a first polarity of the DC power to a center tap of a first transformer winding connected across a distal end of the first twisted pair of conductors;

means for applying a second polarity of the DC power to a center tap of a second transformer winding connected across a distal end of the second twisted pair of conductors;

means for extracting said first polarity from a center tap of a third transformer winding connected across a proximal end of the first twisted pair of conductors; and

means for extracting said second polarity from a center tap of a fourth transformer winding connected across a proximal end of the second twisted pair of conductors.

17. A system according to claim 16 further comprising an uninterruptible power supply for sourcing the DC power.