LM35 Temperature Sensor
LM35 is an integrated analog temperature sensor whose electrical output is proportional to Degree Centigrade. LM35 Sensor does not require any external calibration or trimming to provide typical accuracies. The LM35’s low output impedance, a linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy.
As such no extra components are required to interface LM35 to ADC as the output of LM35 is linear with 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 1°C change.
LM35 can also be directly connected to Arduino. The output of LM35 temperature can also be given to comparator circuit and can be used for over-temperature indication or by using a simple relay can be used as a temperature controller.
The LM35 device is rated to operate over a −55°C to 150°C temperature range, while the LM35C device is rated for a −40°C to 110°C range (−10° with improved accuracy). The LM35-series devices are available packaged in hermetic TO transistor packages, while the LM35C, LM35CA, and LM35D devices are available in the plastic TO-92 transistor package. The LM35D device is available in an 8-lead surface-mount small-outline package and a plastic TO-220 package.
From food processing to medical applications, to petrochemical handling and automotive monitoring, to biological research and geological studies, to HVAC systems and other consumer electronics, temperature sensors are a crucial tool in countless fields. In fact, they’re also used throughout our own homes and offices, within the transport we travel in, and even in devices, we use every day!
1 x LM35 Temperature Sensor
|Maximum Supply Voltage (V)||
|Minimum Supply Voltage (V)||
|Operating Temperature Range (°C)||
-55 to 150
8 × 5 × 3 cm
Frequently Asked Questions
1. How to calculate temperature using LM35 temperature sensor?
- Power LM35 vcc to +5-20 volts and gnd to ground.
Connect Vout to analog to digital converter input.
Sample the ADC reading, vout output voltage.
Convert the voltage to temperature.
The formula to convert the voltage to centigrade temperature for LM35 is
Centigrade Temperature = Voltage Read by ADC / 10 mV(mills Volt)
2. What are the types of temperature sensors?
- Contact temperature sensors
These types need to touch the object that they’re measuring the temperature of, whether it’s a solid, liquid, or gas. They actually just measure their own temperature, but we infer that the temperature of whatever it’s in contact with is in thermal equilibrium (i.e. are the same temperature).
Common types of contact temperatures sensors include thermocouples, RTD’s, thermistors, thermostats, and semiconductor temperature sensors. They should be used when you are able to make good thermal contact between the device and what you’re measuring. It’s also easier to attain continuous monitoring and data collection with contact thermometers.
Non-contact temperature sensors
These determine temperatures from a distance, by measuring the thermal radiation emitted by an object or heat source. The applications for these are often in high temperatures or hazardous environments where you need to maintain a safe distance away from a particular body.
Thermal imaging and infrared sensors are the most common type of non-contact temperature sensors, and are used in the following circumstances: when the target object is moving (such as on a conveyor belt or within moving machinery), if it’s a great distance away if there’s a dangerous surrounding environment (such as high voltages) or at extremely high temperatures where a contact sensor would not function appropriately.