28040 Parallax Inc, 28040 Datasheet - Page 3

• Manufacturer Part Number: 28040
• Description: Board Mount Temperature Sensors Infrared Thermometer 90 Deg Mod MLX90614
• Manufacturer: Parallax Inc

Specifications of 28040

• Temperature Threshold: + 380 C
• Package / Case: SIP-5
• Digital Output - Number Of Bits: 16 bit
• Supply Voltage (max): 5 V
• Description/function: Temperature Sensor
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Supply Current: 20 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

How MLX90614 Infrared Thermometer Modules Work
Using a Parallax SX20AC/SS-G coprocessor, the MLX90614 module receives serial commands from the
BASIC Stamp or other microcontroller, then configures and controls the MLX90614 sensor. Resulting
output data is directed back though the same I/O pin. The READ and WRITE commands conform to
those indicated in the MLX90614 datasheet for writing to the SMBus, an I2C style format.
The MLX90614 sensor has an internal EEPROM, where sensor addresses (for using multiple sensors on a
single bus), alarm values and data transmission intervals are set.
The SMBus protocol between the thermopile sensor and the SX20AC/SS-G coprocessor includes a byte for
the sensor’s packet error code (PEC) calculation. The PEC value isn’t a linear value that shows data
integrity, but a number calculated with a CRC-8 procedure to show whether or not the data is valid which
results in a “pass” or “fail”. Once the correct communication is established between a microcontroller and
MLX90614 module it is not likely to have a failed PEC calculation unless the module is removed from the
circuit during operation.
Upon power up the MLX90614 module will be reading the temperature data held in RAM address $07.
There is a minimum 1 ms delay between each temperature reading. In the non-sleep operation mode the
timing is adjustable from 1 to 2550 ms and can be set in the low data byte of the reading time interval
command address ($21). In the sleep operation mode the timing is adjustable from 1 to 255 seconds and
can be set in the high data byte of the reading time interval command address ($21). It takes
approximately 1 ms to perform a temperature reading. Interval timing for non-sleep and sleep operation
modes have been factory set at 50 ms and 1.15 seconds, respectively.
The MLX90614 module’s alarm can be set between -70 °C and +380 °C in the low and high data bytes of
the alarm command address ($20). The factory default setting is 100 °C.
References
Copyright © Parallax Inc.
1. Melexis MLX90614 datasheet, No. 390109614 Rev. 003, 03 Oct 2007
2. Melexis SMBus communication with MLX90614, No. 390119061402 Rev 001, Oct 2006
3. Melexis Understanding MLX90614 on-chip digital filters, No. 390119061406 Rev 001, Apr 2007
MLX90614 Infrared Thermometer Modules (#28040-28042)
v2.0 11/18/2008 Page 3 of 8