What is Temperature Sensor:
Temperature sensor is a sensor that senses the temperature of the environment or the temperature of the concerned material. Temperature sensing can be done by two ways: either by direct contact with the concerned material or by non-contact which uses the radiated photons of the materials.
There are 5 types of mostly used temperature sensors:
- Resistance Temperature Detectors (RTD)
- Semiconductor Sensors
The temperature sensor used for projects and with is compatible with most of the microcontrollers is semiconductor sensor.
Here we are showing the details of LM35 temperature sensor and interfacing it with Arduino.
LM35 temperature sensor:
The LM35 temperature sensor is a semiconductor sensor. It is available in integrated circuit (IC) form. It has 3 pins and the IC is as shown below.
Working Principle of temperature sensor :
Since LM35 IC is semiconductor IC it is based on the principle that the voltage across a diode varies proportionally with the temperature i.e. if the temperature of the environment varies the current across the diode also varies due to which the voltage across base-emitter junction VBE also varies. The relation between the current and the temperature of the diode is stated below:
Where, VT is actual temperature dependent term which is given by:
VT = kT/q
Features of LM35:
- Calibrated directly in Celsius scale ( Centigrade)
- Linear +10 mV/0C scale factor
- 50C Ensured Accuracy (at 250C)
- Works for -550C to 1500C
- Operates in the range of 4V to 30V
- Less than 60µA design drain current
- Low impedance output, 0.1Ω for 1-mA load
- Low self heating, 0.80C in still air
Here is the temperature sensor project ( temperature monitoring system using AVR atmega16/32) please click the link https://www.electronify.org/avr-projects/thermometer