| 摘要 |
<p>PURPOSE:To allow a backup power source to supply power to a microcomputer to be used for a timer for a long time when power failure occurs by using a frequency oscillator much lower than the clock oscillation frequency of the microcomputer for a time and setting the microcomputer operable only when the oscillation signal comes in. CONSTITUTION:When power failure is detected, the oscillation of a built-in clock oscillator stops. Simultaneously a built-in RAM is in a stop mode attaining a storage holding state. The low frequency oscillator 2 with an oscillation frequency much lower than the clock frequency of the built-in clock oscillator is added to the timer microcomputer 1 which temporarily moves from the stop mode to a normal operation mode when a stop mode release signal is supplied. An oscillation signal from the low frequency oscillator is supplied as the stop mode release signal to the microcomputer 1. In case of power failure, the backup power source 5 can supply power to the microcomputer 1 for a long time.</p> |
