Temperature detecting device

摘要

A temperature detecting device comprises a temperature detecting element such as a thermistor for sensing temperature changes and a MOS-transistor connected in series with the temperature detecting element. A constant voltage source maintains a constant reference voltage. A voltage comparing circuit compares the voltage across the MOS-transistor or the voltage across the temperature detecting element with the constant reference voltage during periods when the MOS-transistor is turned ON and produces an output signal representative of the temperature. A plurality of MOS-transistors can be used in which case they are connected in parallel with each other and are connected in series with the temperature detecting element. The plurality of MOS-transistors are sequentially turned ON to enable the voltage comparing circuit to compare either the voltages across the MOS-transistors or the voltage across the temperature detecting element with the constant reference voltage during the periods when the MOS-transistors are turned ON.