Patent ID: 7187225

Claim:
An electronic control unit powered from a driving power supply and connected to an analog sensor through a wire harness accommodating at least a power supply line and a signal line, comprising: a constant voltage power supply circuit portion for generating a regulated voltage based on the power feeding from the driving power supply; an analog signal inputting circuit portion connected to the constant voltage power supply circuit portion; and a conversion processing circuit portion to which a detection signal from the analog sensor is supplied through the signal line, the analog signal inputting circuit portion comprising: a current limiting circuit portion inserted into a power supply line of the constant voltage power supply circuit portion for powering the analog sensor through the power supply line; an integrating circuit portion inserted between an input signal line connected to the signal line and the conversion processing circuit portion; a current limiting resistor inserted between the input signal line and the integrating circuit portion; a signal noise absorbing circuit portion connected to the power source line, a ground line of the constant voltage power supply circuit portion, and the input signal line; and a first bypass capacitor inserted between an output terminal of the current limiting circuit portion and the ground line, wherein an electrostatic capacity (C 1 ) and a parasitic inductance (L 1 ) of the first bypass capacitor are set in a range expressed by Equation (1): 7×10 6 <1/[2π√( L 1× C 1)]<35×10 6 (1).