Fail-safe inline power in a wired data telecommunications network

• US 8,149,683 B2
• Filed: 05/18/2005
• Issued: 04/03/2012
• Est. Priority Date: 05/18/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Karam, Roger A.
• Primary Examiner(s): BLANTON, JOHN D
• Application Number:
  US11/133,012
• Publication Number:
  US 20060262713A1
• Time in Patent Office: 2,512 Days
• Field of Search: 370/200
• US Class Current: 370/200
• CPC Class Codes: H04L 12/10 Current supply arrangements

Abstract

A dynamic fuse element is provided in an inline power circuit to provide an electrical current protection level that varies in accordance with allocated current levels and that can respond to current spikes that are not expected. The dynamic fuse element comprises a processor aware of allocated current levels and an inline switch controlled by the processor to turn OFF in the event of a fault. In another aspect ferrite fuses may be provided for relatively low-current applications. In yet another aspect test fuses may be placed on the circuit board to verify that fuses used in manufacture operate at a certain current level.

Claims

1. A monitoring circuit for inline power supply circuitry of a circuit board blade, the monitoring circuit comprising:

a current monitor carried by the circuit board blade and configured to measure current supplied from a board level power supply carried by the circuit board blade, the circuit board blade comprising the board level power supply as an on-board power supply, to the inline power supply circuitry carried by the circuit board blade to generate a current measurement value associated with the inline power supply circuitry;

a processor carried by the circuit board blade and associated with the inline power supply circuitry, the processor configured to calculate, over time and as a threshold, a total amount of current allocated to a set of active network ports of a set of network ports associated with the inline power supply control circuitry disposed on the circuit board blade, the set of network ports configured to provide power to a powered device, and the processor configured to receive the current measurement value associated with the circuit board blade from the current monitor; and

a current control device carried by the circuit board blade and coupling the inline power supply circuitry disposed on the circuit board blade to the board level power supply disposed on the circuit board blade, the current control device configured to regulate current flow from the board level power supply disposed on the circuit board blade to the inline power supply circuitry disposed on the circuit board blade, the current control device controlled by the processor;

wherein the processor is configured to;

when the current measurement value associated with the current drawn by the set of active network ports disposed on the circuit board blade exceeds the threshold, detect a current spike having a current spike characteristic,

when the current spike has a first current spike characteristic indicative of an expected increase in current drawn by one or more ports of a set of ports of the circuit board blade, maintain current flow at the current measurement value associated with the circuit board blade through the current control device, and

when the current spike has a second current spike characteristic indicative of a short circuit on the circuit board blade, reduce current flow from the current measurement value associated with the circuit board blade through the current control device,

wherein when calculating, over time and as the threshold, the total amount of current allocated to the set of active network ports of the set of network ports associated with the inline power supply control circuitry, the processor is configured to calculate a dynamically detected threshold by adding, at a given recurring time interval associated with operation of the monitoring circuit, the direct current allocated to each of the active network ports of the set of network ports associated with the inline power supply control circuitry, the dynamically detected threshold representing the total amount of current allocated to the set of network ports at the given time interval during a duration of operation of the monitoring circuit.

2. The monitoring circuit of claim 1, further comprising a notification transmitter responsive to the current spike to transmit a notification to a recipient.

3. The monitoring circuit of claim 1, wherein the first current spike characteristic indicates cycling of power in the inline power circuitry between a disengaged state and an engaged state.

4. The monitoring circuit of claim 1, wherein the second current spike characteristic indicates that the powered device is configured to receive current below the threshold.

5. The monitoring circuit of claim 1, wherein the processor is configured to store a record of the current spike to memory when the current spike has the second current spike characteristic.

6. The monitoring circuit of claim 5, wherein the processor is configured to store a record of the current condition to memory if the current spike has the second current spike characteristic, the record including at least one of a date, a time, a powered port, an amount of current drawn, and a status of the monitoring circuit.

7. The monitoring circuit of claim 1, wherein:

the inline power supply circuitry is standardized to IEEE Standard 802.3af;

the first current spike characteristic indicates that the processor has analyzed the powered device in electrical communication with the monitoring circuit and determined that for that particular powered device the current spike is permissible;

the second current spike characteristic indicates that the processor has analyzed the powered device in electrical communication with the monitoring circuit and determined that for that particular powered device the current spike is impermissible; and

the current control device is configured to operate as an enhanced surge protector to prevent the transmission of the current spike if the current spike is impermissible while allowing the current spike if the current spike is permissible when the current spike has a current value greater than the threshold.

8. The monitoring circuit of claim 1, wherein:

the board level power supply carried by the circuit board blade is configured to connect to a backplane and receive power from a main power supply; and

the circuit board blade carries at least one port configured to provide power to a powered device distinct from the circuit board blade, the inline power supply circuitry configured to provide current to the at least one port carried by the circuit board blade in response to the current control device.

9. The monitoring circuit of claim 1, wherein when calculating the dynamically detected threshold at the given recurring time interval associated with operation of the monitoring circuit, the processor is configured to calculate the dynamically detected threshold over a set of periodic time intervals occurring at a given frequency during the duration of operation of the monitoring circuit.

10. The monitoring circuit of claim 1, wherein when calculating the dynamically detected threshold at a recurring time interval associated with operation of the monitoring circuit, the processor is configured to calculate the dynamically detected threshold in real time during operation of the monitoring circuit.

11. The monitoring circuit of claim 1, wherein when the current measurement value associated with the current drawn by the set of active network ports disposed on the circuit board blade exceeds the dynamically detected threshold, prior to detecting the current spike having the current spike characteristic, the processor is configured to (1) recalculate the sum of allocated direct currents allocated to each of the active network ports of the set of network ports associated with the inline power supply control circuitry and (2) verify the recalculated sum of allocated direct currents allocated to each of the active network ports as being equal to the dynamically detected threshold representing the total amount of current allocated to the set of network ports at the given time interval during a duration of operation of the monitoring circuit.

12. A computer networking system utilizing inline power supply circuitry, the system comprising:

a main power supply;

at least one circuit board blade configured to receive inline power from the main power supply; and

a backplane configured to pass inline power from the main power supply to the at least one circuit board blade, the circuit board blade including a monitoring circuit including;

a current monitor carried by the circuit board blade and configured to measure current supplied from a board level power supply carried by the circuit board blade, the circuit board blade comprising the board level power supply as an on-board power supply, to the inline power supply circuitry carried by the circuit board blade to generate a current measurement value associated with the inline power supply circuitry;

a processor carried by the circuit board blade and associated with the inline power supply circuitry, the processor configured to calculate, over time and as a threshold, a total amount of current allocated to a set of active network ports of a set of network ports associated with the inline power supply control circuitry disposed on the circuit board blade, the set of network ports configured to provide power to a powered device, and the processor configured to receive the current measurement value associated with the circuit board blade from the current monitor; and

a current control device carried by the circuit board blade and coupling the inline power supply circuitry disposed on the circuit board blade to the board level power supply disposed on the circuit board blade, the current control device configured to regulate current flow from the board level power supply disposed on the circuit board blade to the inline power supply circuitry disposed on the circuit board blade, the current control device controlled by the processor;

wherein the processor is configured to;

when the current measurement value associated with the current drawn by the set of active network ports disposed on the circuit board blade exceeds the threshold, detect a current spike having a current spike characteristic,

when the current spike has a first current spike characteristic indicative of an expected increase in current drawn by one or more ports of a set of ports of the circuit board blade, maintain current flow at the current measurement value associated with the circuit board blade through the current control device, and

when the current spike has a second current spike characteristic indicative of a short circuit on the circuit board blade, reduce current flow from the current measurement value associated with the circuit board blade through the current control device,

wherein when calculating, over time and as the threshold, the total amount of current allocated to the set of active network ports of the set of network ports associated with the inline power supply control circuitry, the processor is configured to calculate a dynamically detected threshold by adding, at a given recurring time interval associated with operation of the monitoring circuit, the direct current allocated to each of the active network ports of the set of network ports associated with the inline power supply control circuitry, the dynamically detected threshold representing the total amount of current allocated to the set of network ports at the given time interval during a duration of operation of the monitoring circuit.

13. The computer networking system of claim 12, wherein when calculating the dynamically detected threshold at the given recurring time interval associated with operation of the monitoring circuit, the processor is configured to calculate the dynamically detected threshold over a set of periodic time intervals occurring at a given frequency during the duration of operation of the monitoring circuit.

14. The system of claim 12, wherein the first current spike characteristic indicates cycling of power in the inline power circuitry between an engaged state and a disengaged state.

15. The system of claim 12, wherein the second current spike characteristic indicates that the powered device is configured to receive current below the threshold.

16. The system of claim 12, wherein:

the inline power supply circuitry is standardized to IEEE Standard 802.3af;

the first current spike characteristic indicates that the processor has analyzed the powered device in electrical communication with the monitoring circuit and determined that for that particular powered device the current spike is permissible;

the second current spike characteristic indicates that the processor has analyzed the powered device in electrical communication with the monitoring circuit and determined that for that particular powered device the current spike is impermissible; and

the current control device is configured to operate as an enhanced surge protector to prevent the transmission of the current spike if the current spike is impermissible while allowing the current spike if the current spike is permissible when the current spike has a current value greater than the threshold.

17. The system of claim 16, wherein, when reducing current flow from the current measurement through the current control device, the processor is configured to throttle back available current by modulating a gate of a field effect transistor switch in the current control device using a fold back mechanism that reduces voltage.

18. The system of claim 12, wherein the inline power supply circuitry comprises an inline power controller configured to establish required levels of power supplied to a port carried by the circuit board blade and disposed in electrical communication with the inline power supply, to measure a current drawn by the port, and to supply the processor with data related to the current drawn by the port.

19. The system of claim 18, wherein the inline power supply circuitry comprises a fuse carried by the circuit board blade, the fuse disposed in electrical communication between the inline power controller and the board level power supply, the fuse configured to guard the inline power controller from an over current condition.

20. The system of claim 19, wherein the fuse is configured as a surface mount ferrite bead device, the surface mount ferrite bead device carried by the circuit board blade.

21. The system of claim 18, wherein the inline power supply circuitry comprises a fuse carried by the circuit board blade, the fuse disposed in electrical communication between the inline power controller and the port carried by the circuit board blade.

22. The computer networking system of claim 12, wherein when calculating the dynamically detected threshold at a recurring time interval associated with operation of the monitoring circuit, the processor is configured to calculate the dynamically detected threshold in real time during operation of the monitoring circuit.

23. The computer networking system of claim 12, wherein when the current measurement value associated with the current drawn by the set of active network ports disposed on the circuit board blade exceeds the dynamically detected threshold, prior to detecting the current spike having the current spike characteristic, the processor is configured to (1) recalculate the sum of allocated direct currents allocated to each of the active network ports of the set of network ports associated with the inline power supply control circuitry and (2) verify the recalculated sum of allocated direct currents allocated to each of the active network ports as being equal to the dynamically detected threshold representing the total amount of current allocated to the set of network ports at the given time interval during a duration of operation of the monitoring circuit.

24. A method for monitoring current provided to inline power supply circuitry of a circuit board blade from a board level power supply having a total maximum current supply capacity, the method comprising

measuring a current supplied from a board level power supply carried by the circuit board blade to the inline power supply circuitry carried by the circuit board blade to generate a current measurement value associated with the circuit board blade;

calculating, over time and as a threshold, a total amount of current allocated to a set of active network ports of a set of network ports associated with the inline power supply control circuitry disposed on the circuit board blade, the set of network ports configured to provide power to a powered device;

when the current measurement value associated with the current drawn by the set of active network ports disposed on the circuit board blade exceeds the threshold, detecting a current spike having a current spike characteristic,

when the current spike has a first current spike characteristic indicative of an expected increase in current drawn by one or more ports of a set of ports of the circuit board blade, maintaining current flow at the current measurement value associated with the circuit board blade through the current control device, and

when the current spike has a second current spike characteristic indicative of a short circuit on the circuit board blade, reducing current flow from the current measurement value associated with the circuit board blade, through a current control device, to regulate current flow from the board level power supply to the inline power supply circuitry, the current control device carried by the circuit board blade and coupling the inline power supply circuitry to the board level power supply,

wherein the calculating, over time and as the threshold, the total amount of current allocated to the set of active network ports of the set of network ports associated with the inline power supply control circuitry, includes calculating a dynamically detected threshold by adding, at a given recurring time interval associated with the monitoring method, the direct current allocated to each of the active network ports of the set of network ports associated with the inline power supply control circuitry, the dynamically detected threshold representing the total amount of current allocated to the set of network ports at the given time interval during a duration of operation of the monitoring method.

25. The method of claim 24, wherein the calculating of the dynamically detected threshold at the given recurring time interval associated with operation of the monitoring method includes calculating a dynamically detected threshold over a set of periodic time intervals occurring at a given frequency during the duration of operation of the monitoring method.

26. The method of claim 24, wherein the calculating of the dynamically detected threshold at a recurring time interval associated with operation of the monitoring method includes calculating the dynamically detected threshold in real time during operation of the monitoring method.

27. The method of claim 24, further including, when the current measurement value associated with the current drawn by the set of active network ports disposed on the circuit board blade exceeds the dynamically detected threshold and prior to detecting the current spike having the current spike characteristic, (1) recalculating the sum of allocated direct currents allocated to each of the active network ports of the set of network ports associated with the inline power supply control circuitry and (2) verifying the recalculated sum of allocated direct currents allocated to each of the active network ports as being equal to the dynamically detected threshold representing the total amount of current allocated to the set of network ports at the given time interval during a duration of operation of the monitoring circuit.