Power over ethernet controller integrated circuit architecture
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.
1. A Power Source Equipment (PSE) controller, implemented as part of a PSE, for a Power-over-Ethernet (PoE) communication system, the PSE providing power and data communications to a Powered Device (PD), comprising:
a current measurement system configured to measure a current of the PD to provide a measured current;
a voltage measurement system configured to measure a voltage of the PD to provide a measured voltage;
a temperature measurement system configured to measure a temperature of the current measurement system to provide a measured temperature; and
a multiplexer configured to time-division multiplex the measured current, the measured voltage, and the measured temperature to provide a time-division multiplexed signal including a plurality of channels, the multiplexer being further configured to multiplex the measured current into a first channel from among the plurality of channels, the measured voltage into a second channel from among the plurality of channels, and the measured temperature into a third channel from among the plurality of channels.
2. The PSE controller of claim 1 , wherein the current measurement system comprises:
a main transistor configured to receive the current of the PD; and
a sense transistor configured to replicate the current of the PD passing through the main transistor to provide a replica current.
3. The PSE controller of claim 2 , wherein the current measurement system is further configured to measure the replica current to determine the measured current.
4. The PSE controller of claim 1 , wherein the voltage measurement system comprises:
a buffer amplifier configured to convert the voltage of the PD from a differential signal to a single ended signal, the voltage measurement system being further configured to measure the single ended signal to provide the measured voltage.
5. The PSE controller of claim 1 , wherein the temperature measurement system is further configured to measure a temperature of a junction of a transistor used in the current measurement system.
6. The PSE controller of claim 1 , further comprising:
an analog-to-digital converter (ADC) configured to convert the time-division multiplexed signal from an analog representation to a digital representation.
7. 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 is configured to regulate the supply voltage to provide power to at least one selected from a group consisting of:
the current measurement system,
the voltage measurement system, and
the temperature measurement system.
8. The PSE controller of claim 1 , wherein the PSE controller is coupled to a plurality of ports, the PD being coupled to one of the plurality of ports, the current measurement system, the voltage measurement system, and the temperature measurement system being configured to continuously provide the measured current, the measured voltage, and the measured temperature, respectively, for each of the plurality of ports.
9. The PSE controller of claim 8 , wherein the plurality of channels includes a plurality of first channels, second channels, and third channels, the multiplexer being configured to multiplex the measured current for each of the plurality of ports into a corresponding first channel from among the plurality of first channels, the measured voltage into a corresponding second channel from among the plurality of second channels, and the measured temperature into a corresponding third channel from among the plurality of third channels.
10. The PSE controller of claim 1 , wherein the PSE is configured to provide the power and the data communications to the PD over a common communications link.
11. A method to measure current, voltage, and temperature within a Power over Ethernet (PoE) communication system, the PoE communication system providing power and data communication from a Power Source Equipment (PSE) to a Powered Device (PD), comprising:
measuring, by a PSE controller implemented as part of the PSE, a current of a powered device (PD) to provide a measured current;
measuring, by the PSE controller, a voltage of the PD to provide a measured voltage;
measuring, by the PSE controller, a temperature of the current measurement system to provide a measured temperature; and
time-division multiplexing, by the PSE controller, the measured current, the measured voltage, and the measured temperature to provide a time-division multiplexed signal including a plurality of channels, the measured current being multiplexed into a first channel from among the plurality of channels, the measured voltage being multiplexed into a second channel from among the plurality of channels, and the measured temperature being multiplexed into a third channel from among the plurality of channels.
12. The method of claim 11 , wherein the measuring the current comprises:
receiving, by a main transistor, the current of the PD; and
replicating, by a sense transistor, the current of the PD passing through the main transistor to provide a replica current.
13. The method of claim 12 , wherein the measuring the current comprises:
measuring the replica current to determine the measured current.
14. The method of claim 11 , wherein the measuring the voltage comprises:
converting the voltage of the PD from a differential signal to a single ended signal; and
measuring the single ended signal to provide the measured voltage.
15. The method of claim 11 , wherein the measuring the temperature comprises:
measuring a temperature of a junction of a transistor of the current measurement system to provide the measured temperature.
16. The method of claim 11 , further comprising:
converting the time-division multiplexed signal from an analog representation to a digital representation.
17. The method of claim 11 , further comprising:
regulating a supply voltage to provide power to at least one selected from a group consisting of:
the current measurement system,
the voltage measurement system, and
the temperature measurement system.
18. The method of claim 11 , wherein the measuring the current comprises:
continuously measuring the current of the PD to provide the measured current,
wherein the measuring the voltage comprises:
continuously measuring the voltage of the PD to provide the measured voltage, and
wherein the step of measuring the temperature comprises:
continuously measuring the temperature of the current measurement system to provide the measured temperature.
19. The method of claim 11 , wherein the plurality of channels includes a plurality of first channels, second channels, and third channels, the measured current for each of a plurality of ports being multiplexed into a corresponding first channel from among the plurality of first channels, the measured voltage for each of the plurality of ports being multiplexed into a corresponding second channel from among the plurality of second channels, and the measured temperature for each of the plurality of ports being multiplexed into a corresponding third channel from among the plurality of third channels.
20. The method of claim 11 , further comprising:
providing, by the PSE, the power and the data communications to the PD over a common communications link.