OVER-DISCHARGE PREVENTING CIRCUIT

PROBLEM TO BE SOLVED: To provide an over-discharge preventing circuit which prevents over- discharge of a backup power voltage. SOLUTION: This over-discharge preventing circuit is provided with a backup power voltage 6 (E2 ) supply device, which supplies a backup power voltage 6 (E2 ) to an electronic apparatus supplying a power voltage 1 (E1 ), if the supply of the power voltage 1 (E1 ) to the electronic apparatus is interrupted. In contrast, discharge higher than a discharging level (VB1 ) is prevented, if the prescribed discharging level (VB1 ) of the backup power voltage 6 (E2 ) is detected to shorten the charging time t1 of the backup power voltage 6 (E2 ), at the time of restarting the supply of the power supply voltage 1 (E1 ) for the electronic apparatus with respect to the charging time t2 from a maximum discharging level.