| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To attain a wake-up function for monitoring an analog signal and transferring a microcomputer in a low-power consumption operation mode to a general operation mode with a small circuit scale. <P>SOLUTION: The signal monitoring circuit 5 outputs a wake-up (WP) signal to a microcomputer 3 upon detection that an analog signal Vb from a brake pedal sensor becomes lower than a reference voltage by pressing-down operation of a brake pedal while the microcomputer 3 is in the low power consumption operation mode. The signal monitoring circuits 5 operates cyclically, and when the signal monitoring circuit starts the operation, a capacitor 15 is charged with a constant current from a constant current circuit 17 for only a charging time stored in a memory 10. When a comparator 25 detects that the analog signal Vb is lower than the charge voltage Vc of the capacitor 15, the comparator 25 outputs the wake-up signal to the microcomputer 3. A charging time for making the charge voltage Vc of the capacitor 15 to the reference voltage at the time of completion of charging is pre-stored in the memory 19 by the microcomputer 3. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
