| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a backup power supply circuit capable of preventing an excess rush current into a backup capacitor at reduced cost. <P>SOLUTION: The backup capacitor C1 is disposed in such a manner that if no power is supplied to a power line Vcc from an AC adapter 10 or a battery pack 20, a charge is discharged to the power line Vcc so as to supply a predetermined amount or more of power to the power line Vcc. In a charging path (sign A) leading from the power line Vcc to the positive electrode (+electrode) of the backup capacitor C1, a charging current limiting resistor R8 for limiting a charging current that flows through the charging path is disposed. In a discharge path (sign B) for causing a discharge from the positive electrode (+electrode k) of the backup capacitor C1 to the power line through a path different from the charging path (sign A), a diode D3 that limits the direction of current in the discharge path to only the direction of discharge (direction shown by sign B) is disposed. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
