Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
1995-04-27
2001-03-13
Le, Dieu-Minh T. (Department: 2785)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C713S300000, C307S043000
Reexamination Certificate
active
06202171
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to power management for portable electronic systems. More particularly, the present invention relates to power fault detection and protection methods and mechanisms for portable computer systems having multiple power sources.
ART BACKGROUND
As the computer revolution has progressed, computing machines have become ever smaller, yet more powerful. The advent of advanced semiconductor technologies has resulted in computers that are easily transportable. Today, portable laptop computers which utilize advanced packaging techniques are nearly as common as desktop computers were just a few years ago. The efforts of computer architects today, using emerging technologies, is the ever smaller, faster portable computer that is lightweight, extremely modular and flexible in its use.
An important consideration in designing portable computing devices, or any portable electronic device is the configuration of the power system. Ideally, when a computer is used at a fixed location, the user should be able to plug the device in to an AC-power outlet and derive power for the device by means of an AC adapter or equivalent technology, where DC power is supplied to the computer after being converted from AC by the AC adapter. When the portability aspect of the device is being utilized, and electric wall sockets are unavailable, the portable computer must operate from battery power. While battery technologies are improving, they still suffer the unfortunate characteristics of being large and heavy relative to the overall size and weight of portable devices.
In an effort to meet the above goals of lightweight, modular systems having increased flexibility, computer makers have begun exploring the possibility of providing multiple power sources, including more than one battery compartment. This allows for more flexibility in designing around space constraints in tightly packaged small systems. The price of this increased flexibility is increased complexity with respect to power management subsystems. For example, when more than one battery pack is provided for, the computer system must provide additional battery contacts and provide for the coordination of selecting an optimal operating power source.
Another object of the evolving computer revolution has been to make computers more “friendly”. Computers that lose data or require re-initializing because of power problems are decidedly unfriendly. Further, it is a disadvantage of many systems to have to shut down the computer system when changing from one power supply to another. It would be desirable, and is therefore an object of the present invention, to provide a reliable power supply management system for portable computers having multiple power sources.
SUMMARY OF THE INVENTION
From the foregoing, it can be appreciated that there is a need to provide superior power system control techniques for densely integrated portable electronic systems having multiple power supplies. Accordingly, it is an object of the present invention to provide a method and apparatus for the seamless transition between power sources in a portable computer system having multiple power sources. It is also an object of the present invention to provide a fault detection and protection technique for a computer system that encounters a power fault when operating from one of several available power supplies. It is another object of the present invention to provide a method and apparatus to recover from such power faults in such a way that power source transitions are not disruptive to a running computer system.
These and other objects of the present invention are provided in a preferred embodiment portable computer system that utilizes four (4) available power supplies: power from an AC adapter and power cord, two separate battery power bays, and a state-preserving rechargeable lithium coin-stack battery. During normal computer system operation, only one power source provides power to the components of the computer system. The power management system is driven by a software operated microcontroller which provides driving signals to a Programmable Array Logic (PAL) device for operating the power system's switching circuits.
The power system is provided with fault detection circuitry which monitors the voltage level of the power being supplied to the computer system components. If that supply voltage drops below a threshold level, a safety-net circuit is triggered. The threshold level for activating the safety-net circuit varies depending on whether the system is being powered by an AC line voltage or by a battery.
The safety-net circuit that is triggered upon detection of a power fault provides a fault indicating signal to the PAL. When the fault indicating signal is received by the PAL, it propagates appropriate signals to a plurality of the power system's switches which cause all available power supplies to be bridged through an arrangement of diodes. This guarantees that the load (the computer system) will continue to receive power from the combined power supply available to the system. Additionally, while the fault condition is active, a backup low power regulator is provided with a control signal which turns the regulator on for ensuring that the system's parameter memory and the microcontroller are maintained in a safe state.
Once a power system fault condition has been detected and the available power supplies are bridged by the safety-net circuit, a routine running in the power system microcontroller may begin the process of determining the best way to recover from the power system fault condition in a controlled-fashion (i.e., selecting the appropriate power supply to designate as the system's operating power supply). Once a power supply is designated as the system's power supply, the fault condition transition situation is terminated and the computer system resumes normal operation. The entire process may occur without interruption to a user operating the computer system. This mechanism allows a user to switch from an AC power source to a battery source without halting a running process. Likewise, a user may remove one battery pack and continue operating from the other without having to shut down the system.
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IBM Technical Disclosure Bulletin, vol. 34, No. 1, Jun. 1991, “Fault Indicator Software Support For Unattended Operational Personal Computer Systems”.
Blanc James J.
Townsley David B.
Apple Computer Inc.
Blakely & Sokoloff, Taylor & Zafman
Le Dieu-Minh T.
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