The Melexis MLX90614ESF-AAA is a high-accuracy, high-resolution, non-contact thermometer with a 90-degree field of view.  It has a measurement resolution of 0.02°C and is factory calibrated for a wide -70 to 380°C object temperature range.  The sensor uses an SMBus (I²C-compatible) digital interface and can be configured to output a customizable 10-bit PWM output for continuous readings.

Overview

The MLX90614 family of sensors use infrared thermopile detectors to determine the temperature of objects without touching them. This sensor can tolerate ambient temperatures from -40 to 85°C and works for object temperatures from -70 to 382.2°C. It provides a measurement resolution of 0.02°C and has an accuracy of ±0.5°C at room temperature. The device comes in a compact TO-39 package that weighs just 0.03 oz (0.9g), and it features filters that give it immunity from ambient IR and sunlight. Please see the MLX90614 datasheet (749k pdf) for more information.

Application Examples

• Fire detector on a firefighting robot
• Movement detector
• Thermal relay with a programmable threshold (e.g. for use in a thermostat)
• Body temperature measurement
• Monitoring of component temperatures, such as motor drivers
• Multi-zone temperature control—up to 100 sensors can be read via two common wires

Using the Sensor

The sensor supports two possible interfaces: SMBus (default) and 10-bit PWM output. The SMBus is completely compatible with I²C (also called TWI) buses for frequencies below 100 kHz and can be used to configure and enable the PWM output if so desired. In addition to the sensor’s datasheet, Melexis’s application note on MLX90614 SMBus communication (589k pdf) and our application note on interfacing Orangutans with the MLX90614 help demonstrate how to use this sensor. Please note that accurate readings can only be achieved if the sensor is in thermal equilibrium and under isothermal conditions (i.e. there are no temperature differences across the sensor package). The measured object temperature is the average of all objects in the sensor’s field of view.

Documentation and other information

Application Note: MLX90614ESF SMBus Communication with Orangutan Robot Controllers (Printable PDF: mlx90614esf_smbus_orangutan.pdf) A guide for implementing the SMBus (I²C-compatible) protocol for the MLX90614ESF temperature sensor on the AVR-based Orangutan robot controller series. The guide includes sample code for taking temperature readings.

File downloads

• MLX90614 datasheet (749k pdf). The datasheet for the MLX90614 family of infrared temperature sensors from Melexis.
• SMBus communication with MLX90614 (589k pdf). An application note from Melexis that details how to interface with the MLX90614 temerature sensor using its SMBus and includes sample code for the PIC18 using the Microchip MCC18 compiler.