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. Thermistors are an excellent sensor for applications involving temperature measurement and control. The surface mount temperature sensing thermistors are available in the Chip or MELF style packaging. The chip surface mount thermistors have a solder-coated metallization with end-banded chips. They are offered in the 0402, 0603, 0805 and 1206 surface mount packages. The MELF style thermistors are glass encapsulated. They are offered in the LL-41 MELF, the LL-31 MicroMELF and the LL-34 MiniMELF package sizes. A leadless, top and bottom terminated chip with silver metallization on the top and bottom surfaces is offered in a variety of sizes. Resistances range from 100 and 1,000,000 Ohms and are available with tolerances between 0.5% and 10 % at 25 degrees C. Operating Temperatures range from -40 thru 125 to -55 thru 220 degrees C.

Littelfuse acquired U.S. Sensor Corporation in 2017 and manufactures the surface mount thermistors.