Power over ethernet controller integrated circuit architecture

• US 20070170909A1
• Filed: 01/17/2007
• Published: 07/26/2007
• Est. Priority Date: 01/17/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Chin, David, Vorenkamp, Pieter, Woo, Agnes, Perzow, John, Fujimori, Ichiro, Tammineedi, Anil
• Granted Patent: US 8,432,142 B2
• Time in Patent Office: Days
• US Class Current: 324/76.110
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
• CPC Class Codes: H04B 3/44 Arrangements for feeding power to a repeater along the transmission line
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 12/40045 Details regarding the feeding of energy to the node from the bus
• CPC Class Codes: H04L 25/02 Details ; arrangements for supplying electrical power along data transmission lines systems for transmitting signals via power distribution lines H04B3/54
• CPC Class Codes: Y10S 370/91 Carrier sense multiple access, e.g. ethernet, 10base-t

Abstract

Power over Ethernet (PoE) communication systems provide power and data communications over the same communications link, where a power source device (PSE) provides DC power (for example, 48 volts DC) to a powered device (PD). The DC power is transmitted simultaneously over the same communications medium with the high speed data from one node to the other node. The PSE typically includes a controller that controls the DC power provided to the PD at the second node of the communications link. The PSE controller measures the voltage, current, and temperature of the outgoing and incoming DC supply lines to characterize the power requirements of the PD. In addition, the PSE controller may detect and validate a compatible PD, determine a power classification signature for the validated PD, supply power to the PD, monitor the power, and reduce or remove the power from the PD when the power is no longer requested or required. During detection, if the PSE finds the PD to be non-compatible, the PSE can prevent the application of power to that PD device, protecting the PD from possible damage.

Claims

1. A Power Source Equipment (PSE) controller comprising:

a current measurement system to measure a current of a powered device (PD);

a voltage measurement system to measure a voltage of the PD;

a temperature measurement system to measure a temperature of the current measurement system; and

a multiplexer coupled to the current measurement system, the voltage measurement system, and the temperature measurement system.

2. The PSE controller of claim 1, wherein the current measurement system uses a sense transistor coupled to a current mirror to replicate the current of the PD.

3. The PSE controller of claim 2, wherein the current measurement system measures the replicate current of the PD to determine the current of a powered device (PD).

4. The PSE controller of claim 1, wherein the voltage measurement system includes a buffer amplifier to convert the voltage of the PD to a single ended signal.

5. The PSE controller of claim 1, wherein the temperature measurement measures a temperature of a junction of a transistor used in the current measurement system.

6. The PSE controller of claim 1, wherein an output of the multiplexer includes a current measurement, a voltage measurement, and a temperature measurement.

7. The PSE controller of claim 6, wherein the current measurement, the voltage measurement, and the temperature measurement are time-division multiplexed.

8. The PSE controller of claim 1 further comprising:

an analog to digital converter (ADC) coupled between a microcontroller and the multiplexer.

9. The PSE controller of claim 8, wherein the ADC converts an output of the multiplexer from analog to digital.

10. The PSE controller of claim 1 further comprising:

a switched mode power supply (SMPS) coupled to a power supply having a supply voltage, wherein the SMPS regulates the supply voltage to provide power to at least one of the current measurement system, the voltage measurement system, or the temperature measurement system.

11. A Power Source Equipment (PSE) controller comprising:

a current detection digital to analog converter (IDAC) coupled to a voltage measurement system to measure a current of a powered device (PD);

a classification module coupled to a current measurement system to measure a voltage of the PD;

a multiplexer coupled to the current measurement system and the voltage measurement system; and

a microcontroller core coupled to the multiplexer.

12. The PSE controller of claim 11, wherein the voltage measurement system uses an output of the IDAC to measure a signature resistance and a signature capacitance of the PD.

13. The PSE controller of claim 12, wherein the microcontroller core determines a valid power signature based upon the signature resistance and the signature capacitance of the PD.

14. The PSE controller of claim 11, wherein the current measurement system uses an output of the classification module to measure a classification current of the PD.

15. The PSE controller of claim 14, wherein the microcontroller core determines a classification signature based upon the classification current.

16. The PSE controller of claim 11, wherein the microcontroller core is coupled to a first Inter-Integrated Circuit (I2C) interface and a second Inter-Integrated Circuit (I2C) interface.

17. The PSE controller of claim 11 further comprising:

a switched mode power supply (SMPS) coupled to a power supply having a supply voltage, wherein the SMPS regulates the supply voltage to provide power to at least one of the IDAC, the classification module, the multiplexer, and the microcontroller core.

18. A method for a detecting and classifying a Power Device (PD) coupled to a Power Source Equipment (PSE) controller, the method comprising the steps of:

applying a current to the PD;

measuring a voltage of the PD based upon the current to generate a voltage measurement;

formatting the voltage measurement into a first time slot within a time-division multiplexed data stream;

determining a device signature of the PD based upon the voltage measurement;

applying a voltage to the PD;

measuring a current of the PD based upon the voltage to generate a current measurement;

formatting the current measurement into a second time slot within the time-division multiplexed data stream; and

determining a power classification signature of the PD based upon the current measurement.

19. The method of step 18, wherein the step of determining a device signature, further comprises:

assigning a valid power device signature to a PD when the signature resistance is from 19 kΩ

to 26.5 kΩ and

the signature capacitance is less than 150 nF.

20. The method of step 18, determining a power classification signature of the PD further comprises:

assigning a corresponding class code to the PD based upon the classification current.