Method and system for controlling the supply of power to a circuit card in a ...

(54) METHOD AND SYSTEM FOR

CONTROLLING THE SUPPLY OF POWER
TO A CIRCUIT CARD IN A CARD SHELF
THROUGH AN ACTIVATION SIGNAL

(75) Inventor: Roy L. Beck, Petaluma, CA (US)

(73) Assignee: Cisco Technology, Inc., San Jose, CA (US)

( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 455 days.

(21) Appl. No.: 09/596,228

(22) Filed: Jun. 15, 2000

(51) Int. CI.7 G06F 1/28; G06F 13/00

(52) U.S. CI 713/300; 710/301; 710/302

(58) Field of Search 709/250; 710/302;

713/300, 330

(56) References Cited

U.S. PATENT DOCUMENTS

4,937,806 A * 6/1990 Babson et al 369/75.1

4,977,593 A * 12/1990 Ballance 380/2

5,268,592 A * 12/1993 Bellamy et al 307/43

5,386,567 A * 1/1995 Lien et al 395/700

5,524,254 A * 6/1996 Morgan et al 709/245

5,530,302 A * 6/1996 Hamre et al 307/147

5,613,130 A * 3/1997 Teng et al 713/300

5,726,506 A * 3/1998 Wood 307/147

5.758.102 A * 5/1998 Carey et al 710/302

6,125,417 A * 9/2000 Bailis et al 710/302

6.237.103 Bl * 5/2001 Lam et al 713/330

6,415,346 Bl * 7/2002 Mueller et al 710/302

6,418,481 Bl * 7/2002 Mancusi et al 709/250

OTHER PUBLICATIONS

Vicor Corporation, Hot Swap Capability Eliminates Down Time, Apr. 2000, Rev2, pp. 1^1.*

* cited by examiner

Primary Examiner—-Thomas Lee

(74) Attorney, Agent, or Firm—Baker Botts L.L.P.

(57) ABSTRACT

A method and system for controlling the supply ol power to a circuit card in a card shell includes automatically generating a deactivation signal in response to disconnection ol a non-power link between the circuit card and a backplane ol the card shell. Power is automatically removed Irom a power link between the circuit card and the backplane while the power link is connected in response to the deactivation signal. An activation signal is automatically generated in response to connection ol the non-power link between the circuit card and the backplane. The supply ol power is automatically restored to the power link between the circuit card and the backplane in response to the activation signal. The activation signal and deactivation signal may be disparate values ol a common signal.

39 Claims, 2 Drawing Sheets

1

METHOD AND SYSTEM FOR CONTROLLING THE SUPPLY OF POWER TO A CIRCUIT CARD IN A CARD SHELF THROUGH AN ACTIVATION SIGNAL

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to the field of modular card shelf systems, and more particularly, to a method and system for controlling the supply of power to a circuit card in a card shelf.

BACKGROUND OF THE INVENTION

Telecommunications systems are generally configured as 15 modular card shelf assemblies to optimize space efficiency within a central office or other similar facilities. Card shelves include discrete circuit cards having different functions that communicate with each other and that receive power across a backplane. The circuit cards each individually plug in to 20 the backplane, that allows any card to be easily replaced in the event of failure.

In many applications, some or all of the circuit cards must be hot-swappable in that they can be inserted and extracted from the card shelf while the card shelf is completely 25 powered up and operational. Because the power supply is active during hot-swapping operations, circuit cards being inserted and extracted from the card shelf often arc to the backplane across the power connection pins during insertion and extraction. 30

A traditional technique to solve the arcing problem during hot-swapping operations is to use filtering capacitors on the power connection pins to protect the circuitry. The use of capacitors, however, adds expense to the system, is not reliable, and can affect operational signal characteristics. 35 Another traditional technique to counter arcing is to use connection pins of different lengths in order to control the order at which circuits on the card being swapped are connected to or disconnected from the backplane. This approach requires careful analysis of the order to power up 40 the circuits, is unreliable and involves some amount of arcing.

SUMMARY OF THE INVENTION

45

The present invention provides a method and system for controlling the supply of power to circuit cards in a card shelf that substantially eliminate or reduce the problems and disadvantages associated with previous systems and methods. In particular, the supply of power to power connectors 50 on the backplane for a card is individually controlled to allow the card to be connected to or disconnected from the backplane while power to the connectors, and thus the card, is shut off.

In accordance with one embodiment of the present 55 invention, a method and system for controlling the supply of power to a circuit card in a card shelf includes automatically generating a deactivation signal in response to disconnection of a non-power link between the circuit card and a backplane of the card shelf. Power is automatically removed from a go power link between the circuit card and the backplane while the power link is connected in response to the deactivation signal.

More specifically, in accordance with a particular embodiment of the present invention, the deactivation signal is 65 automatically generated in response to disconnection of a non-power link between the circuit card and the backplane.

2

The non-power link is configured to disconnect prior to disconnection of the power link. The non-power link may include a pin that is shorter than a power pin of the power link.

In accordance with another aspect of the present invention, an activation signal is automatically generated in response to connection of the non-power link between the circuit card and the backplane of the card shelf. The supply of power is automatically restored to the power link between the circuit card and the backplane in response to the activation signal. The activation signal and the deactivation signal may be disparate values of a common signal. In this and other embodiments, the supply of power to the power link is controlled at the power supply.

Technical advantages of the present invention include providing an improved card shelf for a telecommunications node. In particular, the card shelf automatically controls the supply of power to circuit cards to allow the cards to be hot-swapped without arcing. Accordingly, the cards can be safely inserted and/or removed during operation of the node.

Another technical advantage of the present invention includes providing an improved method and system for inserting and extracting circuit cards in an operational card shelf. In particular, the supply of power to power connectors for a card is automatically shut off when the card is disconnected from the backplane. The supply of power to the power connectors is automatically resumed after a replacement card has been connected to the backplane. Accordingly, arcing between the card and the backplane is eliminated during insertion and extraction operations.

Still another technical advantage of the present invention includes providing a method and system for controlling the supply of power to card slots at the power supply. In particular, the supply of power is controlled at the power supply to remove power from backplane connections for a card slot during hot-swapping operations. By controlling the supply of power to the cards at an off-card location, space is saved on the card and additional features may be added.

Yet another technical advantage of the present invention includes providing an improved method and system for providing power to circuit cards during hot swap operations. During card extraction, power is immediately shut off prior to disconnection of the circuit card. During card connection operations, power is ramped up only after connection of the card to the backplane. Thus, circuit powering is completely controlled during card hot-swapping.

Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a card shelf for a telecommunications node in accordance with one embodiment of the present invention;

FIG. 2 is a block diagram illustrating the connection of a circuit card to a power supply of the card shelf of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 3 is a timing diagram illustrating the supply of power to the circuit card of FIG. 2 in response to an activation signal communicated between the circuit card and power supply in accordance with one embodiment of the present invention.