Temperature detecting device

摘要

A temperature detecting device is provided which can reduce manufacturing cost. Provided that the pull-up resistance has a resistance value RP and the heat-sensitive resistance element has a resistance value RT, the voltage (V1) of the heat-sensitive resistance element in the case of the first voltage extraction mode is given by "VCCxRT/(RP+RT)" while the voltage (V2) of the heat-sensitive resistance element in the case of the second voltage extraction mode is given by "VCCxRT/(2RP+RT)". When the two heat-sensitive resistance elements are normally operating (no occurrence of disconnection or short circuit failure), the voltages respectively extracted in the first and second extraction modes have a ratio matching a ratio of the foregoing two equations (V1:V2). Thus, the two heat-sensitive resistance elements can be positively determined for a presence or absence of failure.