Patent ID: 7329967

Claim:
A car electronic control unit, comprising: a battery; a power source to which power is suppliable from the battery; a central processing unit to which a constant voltage (VCC) is suppliable from the power source; an ignition switch operatively coupled between the battery and the power source to control a supply or interruption of a constant voltage that the power source is configured to generate by ON/OFF control thereof; a delay circuit for delaying an OFF signal by a predetermined delay time when the ignition switch is turned off; and an AND circuit arranged to have voltage of the battery directly transmitted thereto via a first diode with the ignition switch turned on so that an output signal of the delay circuit immediately changes from low to high and to input a control signal outputted from the central processing unit and an output signal of the delay circuit; wherein the central processing unit is configured to detect that the power supplied from the battery is interrupted when the ignition switch is turned off, and to change the control signal after lapse of a predetermined time amount after the ignition switch is turned off for interrupting the supply of the constant voltage, the delay time of the delay circuit is set at longer than the predetermined time amount, and the delay circuit further includes first a resistor, a second resistor, a capacitor, and a second diode, with the capacitor being arranged to be directly charged via the second diode and the first resistor with the ignition switch turned on from the battery and to be discharged via the first and second resistors with the ignition switch turned off to change the output signal of the control circuit from high to low after the delay time.