| 摘要 |
PURPOSE:To enable the condition of the disconnection of a thermistor to be surely detected without reducing a temperature detecting accuracy by connecting a diode in the parallel circuit of a characteristic compensating resistor and the thermistor in a direction wherein a voltage is applied to the thermistor. CONSTITUTION:In a normal condition wherein a thermistor Rt is not disconnected, the thermistor Rt forming one arm of a resistance bridge circuit and a characteristic compensating resistor R4 are connected in parallel via a diode D. Thus, a resolution in a temperature detection in a relatively high temperature region can be increased. Further, since the backward diode D is connected between a thermistor disconnection detecting resistor R5 and the characteristic compensating resistor R4, a power supply voltage or an earth voltage is outputted via the thermistor disconnection detecting resistor R5 as a thermistor output voltage when the thermistor Rt is disconnected. Accordingly, since a greatly different voltage from the thermistor output voltage is outputted in the normal condition wherein the thermistor Rt is not disconnected, the condition of the disconnection of the thermistor Rt can be surely detected.
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