A thermistor is a thermally sensitive resistor that exhibits large, predictable and precise changes in electrical resistance when subjected to corresponding changes in the body temperature of the thermistor. An NTC thermistor is a temperature sensing device where resistance decreases with an increase in body temperature. A PTC thermistor is a temperature sensing device where resistance increases with an increase in the body temperature of the thermistor. Thermistors are an excellent sensor for applications involving temperature measurement and control. Typical applications are found in Industrial Controls, Medical Electronics, HVAC-R's, the Aerospace industry, White Goods and Food Handling Equipment. The thermistor chips can be epoxy coated, glass coated or glass encapsulated. Leaded thermistors are offered with radial or axial leads. Lead wires can be Kynar insulated, Teflon insulated or solderable. Resistances range from 100 to 5,000,000 Ohms. Resistance tolerances are offered at 1%, 2%, 3%, 5%, 10% and 20%. Operating temperatures can range from -80 to 135 up to -55 to 300 degrees C.

Littelfuse acquired U.S. Sensor Corporation in 2017 and manufactures leaded NTC and PTC thermistors