Data Sheet
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
3901090614 Page 24 of 52 Data Sheet
Rev 008 February 28, 2013
Example: (see Figure 17 above):
Configuration:
Sensor1 = Ta, Sensor2 = T
obj1
Config Reg[5:4] = 00b,
CT
MINA
0
_
Cxd
T
EEPROMT
A
LRANGEA
30606875.59
64
2.38
100
min_
__
CT
MAXA
60
_
9901534375.153
64
2.38
100
max_
__
xd
T
EEPROMT
A
HRANGEA
CxTTxEEPROMT
LRANGEAHRANGEARANGEA
9930:030,
_____
CT
MINO
0
_
3602731515.273100010,
min__
ABxdTxEEPROMT
OMINO
CT
MAXO
50
_
BExdTxEEPROMT
OMAXO
3703231515.273100000,
min__
Captured high durations are:
Sensor 1 – t = 16.875ms at period T = 100ms thus the duty cycle is
16875.0
100
875.16
1
S
Duty
Sensor 2 – t = 73.125ms at period T = 100ms thus the duty cycle is
73125.0
100
125.73
2
S
Duty
The temperatures are calculated as follows:
MINAMINAMAXASA
TTTStartDutyT
___1
14
CT
A
5.2500600625.016875.04
MINOMINOMAXOSO
TTTStartDutyT
___21
24
CT
O
75.3300505625.073125.04
1
8.5.3 Customizing the temperature range for PWM output
The calculated ambient and object temperatures are stored in RAM with a resolution of 0.01°C (16 bit).
The PWM operates with a 10-bit word so the transmitted temperature is rescaled in order to fit in the desired
range.
For this goal 2 cells in EEPROM are foreseen to store the desired range for To (To
min
and To
max
) and
one for Ta (Ta
range
: the 8MSB are foreseen for Ta
max
and the 8LSB for Ta
min
).
Thus the output range for To can be programmed with an accuracy of 0.01°C, while the corresponding Ta range
can be programmed with an accuracy of 0.64°C.
The object data for PWM is rescaled according to the following equation:
1023
,
EEPROMEEPROMEEPROM
obj
MINMAX
obj
PWM
obj
PWM
MINRAM
PWM
TT
K
K
TT
T