LM35 Temperature Sensor
LM35 overview
Original LM35 Temperature Sensor is an integrated analog temperature sensor whose electrical output is proportional to Degree Centigrade. LM35 Temperature Sensor does not require any external calibration or trimming to provide typical accuracies. The LM35’s low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. The main advantage of LM35 is that it is linear i.e. 10mv/°C which means for every degree rise in temperature the output of LM35 will rise by 10mv. So if the output of LM35 is 220mv/0.22V the temperature will be 22°C. So if the room temperature is 32°C then the output of LM35 will be 320mv i.e. 0.32V.
As such no extra components are required to interface LM35 to ADC as the output of LM35 is linear with a 10mv/degree scale. It can be directly interfaced to any 10 or 12-bit ADC. But if you are using an 8-bit ADC like ADC0808 or ADC0804 an amplifier section will be needed if you require to measure a 1°C change.
LM35 can also be directly connected to Arduino. The output of LM35 temperature can also be given to the comparator circuit and can be used for over-temperature indication or by using a simple relay can be used as a temperature controller
Key specifications
Datasheet
LM35 features
- Calibrated directly in Degree Celsius (Centigrade)
- Linear at 10.0 mV/°C scale factor
- 0.5°C accuracy guarantee-able (at a25°C)
- Rated for full -55°C to a 150°C range
- Suitable for remote applications
- Low cost due to wafer-level trimming
- Operates from 4 to 30 volts
- Less than 60 mA current drain
- Low self-heating, 0.08°C instills an air
- Non-linearity only 0.25°C typical
- Low impedance output, 0.1Ωfor 1 mA load
LM35 pinout
| Name | Description |
|---|---|
| Vcc | Input voltage is +5V for typical applications |
| Analog Out | There will be an increase of 10mV for raise of every 1°C. Can range from -1V(-55°C) to 6V(150°C) |
| Ground | Connected to the ground of the circuit |
LM35 specifications
| Local sensor accuracy (Max) (+/- C) | 0.5 |
|---|---|
| Operating temperature range (C) | -40 to 110,-55 to 150,0 to 100,0 to 70 |
| Supply voltage (Min) (V) | 4 |
| Supply voltage (Max) (V) | 30 |
| Supply current (Max) (uA) | 14 |
| Sensor gain (mV/Deg C) | 10 |
| Rating | Catalog |
| Features | UL Recognized |
| Interface | Analog Output |
LM35 applications
- Temperature monitoring and control in industrial processes
- Climate control in buildings and homes
- Environmental monitoring in agriculture and greenhouse applications
- Thermal management in electronic devices and components
- Weather stations and meteorological instruments
- Medical devices for measuring body temperature
- Food storage and transportation to ensure proper temperature conditions
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