| 摘要 |
A method and apparatus for driving a battery-backed up clock while a computer system is powered-down. The present invention uses an auxiliary power supply, VAUX, to power a microprocessor bus oscillator. The microprocessor bus oscillator is typically a high frequency, highly accurate oscillator. The microprocessor bus oscillator continues to run while the computer system is powered down, but is connected to a wall outlet. Thus, it can be used to synthesize an accurate time base to drive a battery-backed up clock input. A microcontroller, PAL, or other such circuit can be used to convert the high frequency signal from the microprocessor bus oscillator to a frequency suitable for the battery-backed up clock. Thus, a single oscillator is used to keep time for normal operations. Only when the system is moved, or when main power fails, is a battery backed-up crystal oscillator used to keep time. This minimizes the occurrence of timing errors, due to the system being turned off and back on.
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