Electrical computers and digital processing systems: support – Computer power control
Reexamination Certificate
2000-09-06
2001-06-05
Wiley, David A. (Department: 2155)
Electrical computers and digital processing systems: support
Computer power control
Reexamination Certificate
active
06243818
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
This invention relates to the operation of a data network which interconnects different application modules, and more particularly relates to a method and apparatus for powering components on a data network.
B. Description of Related Art
Networks are the means through which commercially-available components or modules, such as computers, may communicate. One of the problems in formulating a network is the means through which power is supplied to the components in the network. The means for power must be reliable to guarantee network operation, accounting for disruptions to the power supply both at a component level and at a network level. When disruptions do occur, the goal is to maintain network operation and prevent loss of data. The means for power must also must comply with the standards of the particular network.
One such standard for a network is the IEEE 1394-1995 protocol (IEEE 1394) which is discussed in an article entitled “IEEE Standard for a High Performance Serial Bus” published by the IEEE. The IEEE 1394 is also referred to in the industry as Firewire™. However, there are several problems when integrating the IEEE 1394 standard in the design of a multiple-module network. For example, the IEEE 1394 standard requires that the physical interface devices which interconnect with the IEEE 1394 bus powered by a galvanically-isolated supply voltage. With only one module supplying network power, and a large number of modules consuming network power, the 1.5 Ampere current sourcing limit imposed by the IEEE 1394 standard (based upon the connector design) is inadequate to supply power to all of the modules.
If one attempts to address the problem by requiring each module to supply its own power only, one looses the ability of the entire network to stay alive in the event of a power failure of a single module, if that module is being used as a network repeater. Further, if the modules are designed as power sources and power loads simultaneously, and the full IEEE 1394 voltage range of 8-40 Volts for power sources is used, it is difficult to determine which module will supply power to another module in the event of the power failure of one or more modules, and hence cannot guarantee reliable network operation. The present invention solves these and other difficulties.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, a power system for a data processing system is provided. The data processing system has a network bus connected to a component wherein the network bus contains a network power line. The power system has a power supply unit connected to the network power line and to the load. The power system also has circuitry connecting the network power bus to the load. The power system further includes a power selection circuit connected between the power supply unit and the network power line for selecting the power supply unit to power the load. Finally, the power system includes a current limiting circuit which protects the power supply unit from excessive current on the network power line.
In accordance with a second aspect of the invention, a power system for a data processing system is provided. The data processing system has a network bus connected to a component wherein the network bus contains a network power line. The power system has a power supply unit connected to the network power line and to the load. The power system also has circuitry connecting the network power bus to the load. The power system further includes a power selection circuit connected between the power supply unit and the network power line for selecting the power supply unit to power the load. Finally, the power system includes an over-voltage circuit for shielding the load from voltage on the network power line which exceeds a predetermined voltage.
In accordance with a third aspect of the invention, a method of powering a component within a data processing system is provided. The component has a power supply and a load and the data processing system has a network bus containing a network power line. The method includes the step of powering the network power line with power from the power supply unit. The method also includes the step of selecting the power supply unit, rather than the network power line, to power the load. In addition, the current is steered from the power supply unit to the load and from the network power line to the load. The method further includes the step of removing the power supplied by power supply unit to the load. The method also includes powering the load by the network power line after the power supplied by the power supply unit to the load is removed.
In accordance with a fourth aspect of the invention, a method of powering a component within a data processing system is provided. The component has a power supply and a load and the data processing system has a network bus containing a network power line. The method includes the step of supplying the power to the network power line by the power supply unit. In addition, the load is powered. The method also includes the step of protecting the load from the network power line in the event of an increase in the network power line voltage greater than a predetermined limit. Further, the method includes the step of protecting the power supply unit from the network power line in the event of a short circuit in the network power line.
Accordingly, a primary object of the invention is to provide a power system which supports an arbitrarily large network.
Another object of the invention is to maintain normal network operation in the event of a local power outage affecting a large number of components.
Another object of the invention is to maintain normal network operation in the event of a short-circuit or open-circuit fault in the network cable's power wires.
A further object of the invention is to configure a component on the network as a power load and, if desired, a power source simultaneously.
Yet a further object of the invention is for a component preferentially to supply power to its own circuitry.
Still another object of the invention is to protect the power supply of each component from current being driven into the power supply.
Still another object of the invention is for each component to be protected against network over-voltage.
Yet another object of the invention is for each component to be protected against a short-circuit.
Still yet another object of the invention is the maintenance of galvanic isolation in accordance with the IEEE 1394 standard.
REFERENCES:
patent: 5578876 (1996-11-01), Crampton
patent: 5592353 (1997-01-01), Shinohara et al.
patent: 5612580 (1997-03-01), Janonis et al.
patent: 5745670 (1998-04-01), Linde
Schwan Martin A. K.
Sullivan John M.
3Com Corporation
McDonnell & Boehnen Hulbert & Berghoff
Wiley David A.
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