This part is a kind of semiconductor called LM335.

Function of this product has Precision Temperature Sensors.

Manufacturers : National Semiconductor

Image and pinout :

Some of the text within the PDF file :

LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors May 1999 LM135/LM235/LM335, LM135A/LM235A/LM335A Precision Temperature Sensors General Description The LM135 series are precision, easily-calibrated, integrated circuit temperature sensors. Operating as a 2-terminal zener, the LM135 has a breakdown voltage directly proportional to absolute temperature at +10 mV/˚K. With less than 1Ω dynamic impedance the device operates over a current range of 400 µA to 5 mA with virtually no change in performance. When calibrated at 25˚C the LM135 has typically less than 1˚C error over a 100˚C temperature range. Unlike other sensors the LM135 has a linear output. Applications for the LM135 include almost any type of temperature sensing over a −55˚C to +150˚C temperature ran [ ... ]

LM335 PDF Datasheet Download