LM135/235/335 Centigrade Thermometer

LM135/235/335 temperature sensor is designed ease absolute temperature reading, giving all positive value for any frequency, that’s why we read 2.7315V at 0 Celsius degree. To read directly in Celcius, we can use the following circuit:

Centigrade thermometer

This circuit works by nothing more than providing a 2.7315 voltage reference, so you must connect the meter the sensor output and this reference point, not  the ground. [Source: STMicroelectronics Application Note]