| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problems wherein conventional disconnection detection by a power supply circuit is constituted to be performed at a conduction-off time, to thereby sometimes cause increase of a dark current at the conduction-off time, or since a current value flowing in a load is detected, a current detection circuit is required to be installed separately, to thereby increase cost. <P>SOLUTION: In this power supply circuit 1 equipped with a disconnection detection circuit 3, a current is allowed to flow into the load 21 by a low constant-current source I1 at the conduction-on time when power supply to the load 21 is started, and disconnection detection between the load 21 and the power supply circuit 1 is performed by the disconnection detection circuit 3 based on a voltage (output voltage Vout) of the load 21, and thereafter direct power supply is performed from an external power source Vcc to the load 21. <P>COPYRIGHT: (C)2008,JPO&INPIT |
