Non-Contact Human Body Infrared Temperature Module-MLX90614 ESF:
The MLX90614 is a Contactless Infrared (IR) Digital Temperature Sensor that can be used to measure the temperature of a particular object ranging from -70° C to 382.2°C.
The sensor uses IR rays to measure the temperature of the object without any physical contact and communicates to the microcontroller using the I2C protocol.
MLX90614 Pinout Configuration:
| PIN NO | PIN NAME | PIN DESCRIPTION |
| 1 | Vdd (Power supply) | Vdd can be used to power 5V |
| 2 | Ground | The metal can also act as ground |
| 3 | SDA | Serial Data Serial data pin used for I2C |
| 4 | SCL | Serial Clock Serial Clock Pin used for I2C |
The MLX90614 ESF is an Infra-Red thermometer for non-contact temperature measurements. Both the IR sensitive thermopile detector chip and the signal conditioning ASIC are integrated into the same TO-39 can.
The Integrated MLX90614 GY-906 is a low noise amplifier, 17-bit ADC, and powerful DSP unit thus achieving high accuracy and resolution of the thermometer.
The user can configure the digital output to be PWM. As a standard, the 10-bit PWM is configured to continuously transmit the measured temperature in the range of -20 to 120 °C, with an output resolution of 0.14 °C.
Working Principle of MLX90614:
As mentioned earlier, the MLX90614 sensor can measure the temperature of an object without any physical contact with it.
This is made possible with a law called Stefan-Boltzmann Law, which states that all objects and living beings emit IR Energy and the intensity of this emitted IR energy will be directly proportional to the temperature of that object or living being.
So the MLX90614 sensor calculates the temperature of an object by measuring the amount of IR energy emitted from it.
How to use MLX90614 Thermometer Sensor:
The MLX90614 Temperature sensor is manufactured by a company called Melexis.
The sensor is factory calibrated and hence it acts like a plug and play sensor module for speeding up development processes.
The MLX90614 consists of two devices embedded as a single sensor, one device acts as a sensing unit and the other device acts as a processing unit.
The sensing unit an Infrared Thermopile Detector called MLX81101 which senses the temperature and the processing unit is a Single Conditioning ASSP called MLX90302 which converts the signal from the sensor to digital value and communicates using I2C protocol.
The MLX90302 has a low noise amplifier, 17-bit ADC and a powerful DSP which helps the sensor to have high accuracy and resolution.
The sensor requires no external components and can be directly interfaced with a microcontroller like Arduino. As you can see above the power pins (Vdd and Gnd) can be directly used to power the sensor, typically 5V can be used, but there are other versions of this sensor which can operate on 3.3V and 7V as well.
The capacitor C1 is optional and is used to filter noise and provide optimum EMC. The signal pins (SCL and SDA) for used for I2C communication and can be connected directly to microcontroller operating on 5V logic.
The sensor is also sold as a module as you can see in the pinout image. But the sensor module is very similar to the sensor itself and does not have any additional components other than the sensor itself.
Applications of MLX90614:
1. Temperature Measurement of moving objects
2. Industrial Thermal Gun
3. Human Body Temperature Measurement
4. Home/Office Temperature Control
5. Livestock Monitoring
6. Movement Detection
7. Healthcare
8. Multiple zone temperature control – up to 127 sensors can be read via common 2 wires
9. Thermal relay/alert
10. Body temperature measurement
Features:
1. Works from 3.3V to 5V input, Module has power regulator IC built-in.
2. Standard I2C interface with built 2x pull up resistors
3. When measuring the temperature, please maintain a measuring distance of 1 cm
4. Small size, low cost
5. Easy to integrate
6. Factory calibrated in a wide temperature range: -40 to 125 °C for sensor temperature and -70 to 380 °C
7. High accuracy of 0.5°C over the wide temperature range (0..+50 C for both Ta and To)
8. Medical accuracy of 0.1°C in a limited temperature range available on request
9. The measurement resolution of 0.01°C
10. SMBus compatible digital interface for fast temperature readings and building sensor networks
11. Customizable PWM output for continuous reading
12. Simple adaptation for 8 to 16V application.
