MLX90621

16x4 IR array

Datasheet

39001090621

Page 14 of 44

Datasheet IR16x4

Rev 3.0

15 September 2016

Calculation

7.3.

Calculation of absolute chip temperature Ta (sensor temperature)

7.3.1.

The output signal of the IR sensors is relative to the cold junction temperature. That is why we need to know the

temperature of the die in order to be able to calculate the object temperature ‘seen’ by each pixel.

The Ta can be calculated using the formula:

6

_ =

425,8>=

Constants

)

25

(

TH

V

,

1

T

K

and

2

T

K

are stored in EEPROM at following addresses as two’s complement values:

EEPROM address

Cell name

Stored as

Parameter

0xDA

2’s complement

0xDB

0xDC

2’s complement

0xDD

0xDE

2’s complement

0xDF

0xD2

unsigned

Table 5 EEPROM parameters for Ta calculations