LM35 Temperature Sensor
The LM35 Temperature Sensor are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius or Centigrade temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in Kelvin. the user need not do any external calibration or trimming to provide typical accuracies of ±1⁄4C at room temperature and ±3⁄4C over a full −55 to +150C temperature range. It gives accuracy by trimming and calibration at the wafer level. The LM35’s low output impedance, linear output, and precise inherent calibration make lm35dz temperature sensor circuit especially easy. It is applicable to single power supplies or with plus and minus supplies. As it draws only 60 µA from its supply, it has very low self-heating, less than 0.1C in still air. The LM35 can operate over a −55 to +150C temperature range, while the LM35C −40 to the +110C range, −10 with improved accuracy.
The LM35 series is available in different packaged like hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also available in the plastic TO-92 transistor package. The LM35D is also available on an 8-lead surface to mount small outline package and a plastic TO-220 package.
Calibrated directly in Celsius (Centigrade)
Linear + 10.0 mV/C scale factor
5C accuracy guaranteeable (at +25C)
Rated for full −55 to +150C range
Suitable for remote applications
Low cost due to wafer-level trimming
Operates from 4 to 30 volts
Less than 60 µA current drain
Low self-heating, 0.08C in still air n Nonlinearity only ±1⁄4C typical
Low impedance output, 0.1 for 1 mA load
the lm35 temperature sensor circuit
As such no extra components required to interface LM35 to ADC as the output of LM35 is linear with 10mv/degree scale. any 10 or 12 bit ADC interfaced directly with lm35. But if you are using an 8-bit ADC like ADC0808 or ADC0804 an amplifier section will be useful if you require measuring 1°C change.
LM35 directly connected to Arduino. The output of LM35 temperature goes to comparator circuit and used for over temperature indication or by using a simple relay, used as a temperature controller.