The LM135, LM235, LM335 are precision temperature sensors which can be easily calibrated. They operate as a 2-terminal Zener and the breakdown voltage is directly proportional to the absolute temperature at 10mV/°K.
These are Burr Brown Devices from TI. The BB Chips are excellent devices and High Precision, but a bit more expensive. These can be used when customer demands a Higher Quality and Precision. These are good for High Reliability Industrial Instrumentation. - delabs