Temperature detecting device

Abstract

A temperature detecting device comprises a semiconductor diode temperature sensor having a resistance characteristic which varies with variations in temperature, and a constant current circuit connected in series. A power source is connected in parallel with the series circuit and connected in parallel with a constant voltage circuit. A resistance ladder circuit is connected between an output terminal of the constant voltage circuit and one terminal of the power source, and an output terminal of the resistance ladder circuit is connected to a first input terminal of a differential amplifier. A second input terminal of the differential amplifier is connected to a connection point of the semiconductor diode and the constant current circuit. In operation, the voltage drops across cumulatively successive resistors of the resistance ladder circuit are compared with the voltage drop across the semiconductor diode temperature sensor by the differential amplifier and in response to a favorable comparison, the output logic state of the differential amplifier changes to thereby provide an output temperature signal.

Dependencies are inferred from the claim text.