| 摘要 |
<p>PURPOSE:To back up a memory for a long time by using a battery to back up the memory only when a commercial power supply is cut off. CONSTITUTION:A back-up device for a memory 5 consists of a power supply 1, a battery 4 and switching means 2 and 3. Then the memory 5 is backed up by the battery 4 when the power supply 1 is cut off. Here the power supply 1 is cut off by the power supply cut-off signal and at the same time the memory 5 is backed up by the battery 4 only when a commercial power supply AC is cut off. In this respect, a power supply ExVcc that can be cut off only when the power supply AC is cut off. Then the supply of power is cut by the power supply cut-off signal to the devices excluding the memory 5. While the power is supplied to the memory 5 from the power supply ExVcc. Thus the memory 5 is backed up by the battery 4 only when the power supply AC is cut off. This can increase the memory back-up time.</p> |
