| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply control circuit capable of preventing an output transistor from being non-conduction although a power supply reverse connection protective circuit is provided when an overvoltage protective circuit provided for protection of an output transistor against a load surge voltage erroneously operates in reversely connecting the power supply. <P>SOLUTION: The power supply control circuit includes: an output transistor 109 connected between a first power supply line 101 and an output terminal 106; a load 112 connected between the output terminal and a second power supply line 102; an overvoltage protective circuit including a switch transistor 110 connected between a control terminal of the output transistor 109 and the first power supply line 101 and brought into a conduction state with respect to a counter electromotive voltage from the load; and a power supply reverse connection protective circuit for forming an electric path for the control terminal of the output transistor when the power supply is reversely connected to the power supply line. The power supply control circuit is further provided with a reference voltage control circuit 131 for selecting, as a reference voltage given by the switch transistor 110, a voltage of the second power supply line if the power supply is correctly connected and a voltage of the first power supply line when the power supply is reversely connected. <P>COPYRIGHT: (C)2009,JPO&INPIT |
