MLX90614_15 Datasheet, PDF (28/51 Pages) Melexis Microelectronic Systems – Single and Dual Zone Infra Red Thermometer in TO-39

MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
8.7.3 Calculation flow
The measurement, calculation and linearization are held by core, which executes a program form ROM.
After POR the chip is initialized with calibration data from EEPROM. During this phase the number of IR
sensors is selected and it is decided which temperature sensor will be used. Measurements, compensation and
linearization routines run in a closed loop afterwards.
Processing ambient temperature includes:
Offset measurement with fixed length FIR filter
Additional filtering with fixed length IIR filter. The result is stored into RAM as T_OS
Temperature sensor measurement using programmable length FIR *.
Offset compensation
Additional processing with programmable length IIR **. The result is stored into RAM as T_D.
Calculation of the ambient temperature. The result is stored into RAM address 0x06 as T_A
Processing of the object temperature consists of three parts.
The first one is common for both IR sensors, the third part can be skipped if only one IR sensor is used.
IR offset:
Offset measurement with a fixed length FIR
Additional filtering with a fixed length IIR. The result is stored into RAM as IR_OS.
Gain measurement with fixed length FIR filter
Offset compensation
Additional gain filtering with fixed length IIR, storing the result into RAM as IR_G.
Gain compensation calculation, the result is stored into RAM as K_G
Object temperature:
IR1_D.
IR1 sensor:
IR sensor measurement with programmable length FIR filter *.
Offset compensation
Gain compensation
Filtering with programmable length IIR filter**, storing the result into RAM address 0x04 as
Calculation of the object temperature. The result is available in RAM address 0x07 as T_O1.
IR2 sensor:
IR sensor measurement with programmable length FIR filter *.
Offset compensation
Gain compensation
Filtering with programmable length IIR filter**, storing the result into RAM address 0x05 as IR2_D
Calculation of the object temperature. The result is available in RAM address 0x08 as T_O2
PWM calculation:
Recalculate the data for PWM with 10 bit resolution
Load data into PWM module
Note*: The measurements with programmable filter length for FIR filter use the same EEPROM cells for N.
Note**: The IIR filter with programmable filter length uses the same EEPROM cells for L.
3901090614
Rev 009
Page 28 of 52
Data Sheet
June 29, 2015