| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an LED power source control circuit for realizing long time operation of a portable apparatus by turning on an LED, by supplying power directly from a secondary battery when its voltage is high, and restraining supply from a charge pump as a driving power source to the necessary minimum. SOLUTION: The LED power source control circuit is provided with a charging circuit 8 in which one end is connected with an external power source terminal 4, and the other terminal is connected with one end of the secondary battery 9 to be charged; a decision circuit which is connected with one end of the secondary battery 9, decides which of a charge pump circuit 5 or the secondary battery 9 is made an LED driving power source, and performs switching thereof; an LED 7 connected with an LED driving power source terminal 10; and an LED driving circuit 6.</p> |
