| 摘要 |
PROBLEM TO BE SOLVED: To reduce the power consumption of a battery and prolong the available time of a lamp, by detecting a voltage and changing the mode of a step-up circuit into a low-power mode, at battery exhaustion. SOLUTION: A protective circuit 41 detects a voltage drop of a battery 24. When the voltage of the battery 24 is made lower than a fixed voltage (REF), the voltage of a SEL terminal of a DC/DC converter 33 is switched from a High level to a Low level, so that the mode of the DC/DC converter 33 can be changed into the low-power mode. COPYRIGHT: (C)2004,JPO
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