| 摘要 |
PROBLEM TO BE SOLVED: To make power consumption small in the power supply of an electronic apparatus, having a back-up battery and make control simple in a power- supply circuit simple. SOLUTION: In a DC/DC power supply 32, operational power of a system equipment 40 is fed from the output of an AC adapter 30, and an auxiliary rechargeable/dischargeable battery 37 in the system device 40 is provided with the power. In this case, an error amplifier 33 generates a control signal (error signal) to a DC/DC power supply unit 32 for controlling the DC/DC power supply unit 32 in such a way that an output power P0 from the DC/DC power supply unit 32 is always at a given level or below, regardless of a consumption current Is of the system equipment 40.
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