| 摘要 |
PURPOSE:To reduce a mounting area, number of components and to reduce a cost, weight, thickness, length and size of a device by automatically switching a battery to a power source of an AC adapter by an attaching/detaching difference of a connector of the adapter. CONSTITUTION:If an ACADP 13 is connected between connectors 15b and 15c, since a current flows in a circuit of the ACADP 13, the connector 15, a point D, R19, a point C, a DI 17, a point B, a point A, a Ni-Cd cell 16, F, a connector 15C and the ACADP 13, a gate potential of an FET 18 grounded to the ground via R19 and R20 is raised at the time of nonconnection, and a VGS of the FET 18 becomes equal to a forward drop voltage of the DI 17. Here, if the used DI 17 for generating a forward drop voltage of gate cut-off voltage or less of the FET 18 is set, the FET 18 is turned OFF. As a result, a current supply from the cell 16 to a device circuit 2 is interrupted. |
