| 摘要 |
PROBLEM TO BE SOLVED: To provide a power circuit which is small in the number of item parts and a mounting area and is inexpensive, and permits an on board control unit to be placed into a low consumption current mode completely when the system power is turned on or gently rises. SOLUTION: When a system switch 102 is turned on, a backup power 104 acts, and a microcomputer 107 starts to operate. The consuming current of the microcomputer 107 is large, therefore the voltage between the base and the emitter of a transistor 109a in a current boost circuit 109 rises, and the transistor 109a turns on, so that current boost is started. When the microcomputer 107 is placed into a low consuming current mode, a current boost circuit 109 no longer operates, and a power circuit B is also placed into a low consumption current mode. |
