| 摘要 |
<p>PROBLEM TO BE SOLVED: To simplify the structure of a power supply circuit for vehicle which supplies power to a control unit of an on-vehicle apparatus at the time of turning on and off an ignition switch, and reduce the number of parts. SOLUTION: When an ignition switch 8 is ON, a voltage suppressing means 2 is bypassed by a switching transistor 12, and the constant voltage of a constant voltage circuit 1 is supplied to a control unit 4. When the ignition switch 8 is OFF, the bypass of the voltage suppressing means 2 is released, and the constant voltage of the constant voltage circuit 1 is decreased by the voltage suppressing means 2 for supply. It is thus possible to conduct power supply at the time of turning on and off the ignition switch 8, using a single constant voltage circuit.</p> |
