Infrared Thermometer - MLX90614

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Infrared Thermometer MLX90614.jpg

Melexis' MLX90614ESF-BAA is an infrared thermometer designed for non-contact temperature sensing. An internal 17-bit ADC and a powerful DSP contribute to the MLX90614's high accuracy and resolution. It has a huge number of applications including body temperature measurment and movement detection.

The MLX90614 provides two methods of output: PWM and SMBus (i.e. TWI, I2C). The 10-bit PWM output provides a resolution of 0.14°C, while the TWI interface has a resolution of 0.02°C. The MLX90614 is factory calibrated in wide temperature ranges: -40 to 85°C for the ambient temperature and -70 to 382.2°C for the object temperature. The measured value is the average temperature of all objects in the Field Of View of the sensor. The MLX90614 offers a standard accuracy of 0.5°C around room temperatures.

This devices comes in an industry standard TO-39 package. We're carrying the 3V version of this sensor.

Features:

  • Small size, low cost
  • Easy to integrate
  • Factory calibrated in wide temperature range:


-40 to +85°C for sensor temperature

  • -70 to +380°C for object temperature
  • SMBus compatible digital interface
  • Customizable PWM output for continuous reading
  • High accuracy of 0.5°C over wide temperature range (0 to +50°C for both Ta and To)
  • Measurement resolution of 0.02°C
  • Single and dual zone versions
  • Simple adaptation for 8 to 16V applications
  • Power saving mode
  • Different package options for applications and measurements versatility
  • Automotive grade

Contents

Hooking it up

The pins are numbered counter-clockwise from the small pin on the casing while looking at the top of the module.

Pin Number Function Description
1 SCL / Vz Serial clock input for 2 wire communications protocol. 5.7V zener is available at this pin for connection of external bipolar transistor to MLX90614A to supply the device from external 8 …16V source.
2 PWM / SDA Digital input / output. In normal mode the measured object temperature is available at this pin Pulse

Width Modulated.

In SMBus compatible mode automatically configured as open drain NMOS.
3 VDD External supply voltage.
4 VSS Ground. The metal can is also connected to this pin.

The Melexis SMBus transfer datasheet shows this as the communication psuedocode:

Pseudo code example: Reading RAM address 0x07 (Tobj1)

  • 1. Send START bit
  • 2. Send Slave Address (0x00* for example) + Rd\-Wr bit**
  • 3. Send Command (0b000x_xxxx + 0b0000_0111 -> 0b0000_0111)
  • 4. Send Repeated START_bit
  • 5. Send Slave Address + Rd\-Wr bit**
  • 6. Read Data Byte Low (master must send ACK bit)
  • 7. Read Data Byte High (master must send ACK bit)
  • 8. Read PEC (master can send ACK or NACK)
  • 9. Send STOP bit

Note* : Any MLX90614 will respond to address 0x00

Note**: Bit Rd\-Wr has no meaning for MLX90614

Code

Availability

Modules using this component

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