| 摘要 |
<p>A battery powered device is able to maintain a clock value when the battery is removed for a short period. During a first time period, while the battery is in the device, clock pulses derived from a first oscillator are counted at a first rate in a first counter that represents the clock value. During a second time period following the first time period, while the battery is removed, the value of the first counter is maintained independent of any clock pulses derived from the first oscillator, clock pulses derived from a second low power oscillator are counted in a second counter. During a recovery time period following the second time period, clock pulses derived from the second oscillator are again counted in the second counter, while clock pulses derived from the first oscillator are counted in the first counter at a second rate higher than the first rate, the duration of the recovery time period being determined based on the number of pulses counted in the second counter during the second time period.</p> |
