Data Sheet
MLX90640 32x24 IR array
Datasheet
Page 35 of 60
REVISION 11 – 3 AUGUST 2018
11.2.2.
11.2.2.11.2.2.
11.2.2. Temperature calculation
Temperature calculationTemperature calculation
Temperature calculation
After the parameters restore the temperature calculation is done using following calculation flow (assuming that the
EEPROM data are already extracted):
Figure 16 To calculation flow
For this example we calculate the temperature of pixel (12, 16) i.e. row=12 and the column=16.
Values marked with green are extracted from device EEPROM
Values marked with grey are final parameter values or are values to be used for next calculations
11.2.2.1.
11.2.2.1.11.2.2.1.
11.2.2.1. Resolution restore
Resolution restoreResolution restore
Resolution restore
The device is calibrated with default resolution setting = 2 (corresponding to ADC resolution set to 18bit see Fig 11) i.e.
if the one choose to change the ADC resolution setting to a different one a correction of the data must be done. First
we must restore the resolution at which the device has been calibrated which is stored at EERPOM 0x2438.
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Supply voltage value calculation
(common for all pixels)
-
11
.2.2.2
Ambient temperature calculation (common for all pixels) - 11.2.2.3
Gain compensation - 11.2.2.5.1
IR data compensation
–
offset, VDD and Ta
-
11.2.2.5.3
IR data Emissivity compensation
-
11.2.2.5.4
IR data gradient compensation - 11.2.2.7
Normalizing to sensitivity - 11.2.2.8
Calculating To - 11.2.2.9
Image (data) processing