| 摘要 |
PROBLEM TO BE SOLVED: To achieve a long-hour operation of a portable apparatus by, in such charged state as a power is applied from an external power source terminal, suspending the supply of an LED driving voltage from a secondary battery while the power from the external power source terminal is supplied, for a high precision charge with some suitable steps against consumption by the LED after charge. SOLUTION: In a charge mode in which the power is applied from an external power source terminal 1, a charge pump circuit 6 for outputting a voltage to an LED driving voltage terminal 2 is turned off so that a power is supplied to the LED driving voltage terminal 2 from the external power source terminal 1 through a diode 10. Based on the power supplied to the LED driving voltage terminal 2, an LED 7 is lit by the operation of an LED driving circuit 8. The consumption with the LED driving voltage is suppressed till the use of the secondary battery 9 is started since the secondary battery 9 is charged precisely with a voltage from a charge circuit 5 while the LED 7 is driven with the voltage supplied from the external power source terminal 1 in a charged state.
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