Thermistor temperature reference included Large signal; low temperature coefficient of sensitivity Ideally suited for ear thermometers, miniature pyrometers The TPS 333 is an extremely small thermopile detector employing a chip of 0.7 x 0.7 mm2 absorber size and a 100 kV thermistor as temperature reference. The square window opening is equipped with a 5.5 mm longpass (standard) infrared filter. The detector shows a constant sensitivity characteristics over the wavelength.