| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply in which a switch can be turned on/off through a simple arrangement while reducing the size and cost. SOLUTION: A MOSFETQ1 is provided between a battery B and an LED20 and a capacitor C1 is connected in parallel with the LED20 on the downstream side of the MOSFETQ1. A comparator CP1 compares a voltage corresponding to the voltage across the capacitor C1 with a threshold voltage and turns the MOSFETQ1 on if it is lower than the threshold voltage. When the MOSFETQ1 is turned on, a load current IL is supplied from the battery B to the LED20 and the capacitor C1 is charged. Consequently, the voltage corresponding to the voltage across the capacitor C1 increases and when the threshold voltage is exceeded, the comparator CP1 turns the MOSFETQ1 off and the load current IL is supplied from the capacitor C1 to the LED20. COPYRIGHT: (C)2006,JPO&NCIPI
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