| 摘要 |
PURPOSE:To provide a resistance value measuring device which can accurately detect the resistance values of a plurality of variable resistors without increasing its cost and packaging space. CONSTITUTION:An A/D converter 76, pullup resistors R1-R3 connected respectively to a water temperature sensor 38, an intake temperature sensor 40 and an exhaust gas temperature sensor 42, and a pullup resistor R4 connected to a 5-V power supply at one end and to a high-precision resistor Ro at the other, are formed inside an A/D converter IC 62 provided in an engine-controlling ECU (electronic control unit). The water temperature sensor 38 is connected to the 5-V power supply at one end and has a thermistor at the other end. Since the relative errors of the resistors formed inside the same IC are reduced to small values, first the resistance value of the pullup resistor R4 is calculated from the value V4 of a divided voltage produced at the point P4 of connection between the pullup resistor R4 and the high-precision resistor Ro, and the resistance values of the other pullup resistors R1-R3 are then estimated from the value V4, thereby calculating the resistance value of each sensor 38, 40, 42. |
