| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply control circuit, where the power from a battery is efficiently utilized and overcurrent will not flow into the battery. SOLUTION: When an AC adapter 11 is disconnected from a connector 12, the gate voltage of a N-channel FET 25 drops, the N-channel FET 25 is turned off, the gate of a P-channel FET 23 is connected with a ground point through a resistor 26, and the P-channel FET 23 is turned on. As a result, power is supplied from the battery 21 to a load 10. When the AC adapter 11 is connected to the connector 12, a capacitor 19 is charged gradually. When the gate voltage of a N-channel FET 17 reaches a certain voltage, the N-channel FET 17 is turned on, the gate of a P-channel FET 14 is grounded, and the P-channel FET 14 is turned on. As a result, power is supplied from the AC adapter 11 to the load 10. |
