| 摘要 |
PURPOSE: To prevent erroneous function of a microcomputer when the voltage of a backup battery in a backup power supply circuit drops. CONSTITUTION: The backup power supply circuit comprises circuits 4, 5 for detecting the battery voltage being fed to a microcomputer 8. When a data must be erased even if the battery voltage is higher than the lowest level for retaining the data in a memory, a backup battery 3 is discharged until the voltage thereof drops below the lowest data retaining voltage level thus erasing the data. |
