| 摘要 |
PURPOSE:To obtain a backup power circuit, the backup guarantee time of which at the time of service interruption is lengthened and which fills the role even in service interruption immediately after the start of the operation of an equipment by constituting a capacitor for the backup of a micor-computer so that the capacitor can be charged even from the power supply of the equipment. CONSTITUTION:Since the capacity of a capacitor 3 for backup is increased in order to lengthen the backup guarantee time at the time of service interruption, a resistor 4 for charge and discharge is scaled up, and the charging time is lengthened. Consequently, the capacitor 3 for backup is charged slowly from a power input 1 immediately after a power supply is turned ON, but the power input terminal 2 of a micro-computer can be supplied with sufficient currents, thus driving the micro-computer to start the operation of an equipment. Accordingly, currents flow through the base of a transistor 9 through a resistor 7 from a power supply 6 for the equipment, and the transistor 9 turns conductive and the capacitor 3 for backup is charged in a short time through a charging circuit composed of the resistor 7, a constant voltage diode 8 and the transistor 9. |
