Data Sheet

MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
8.5 PWM
The MLX90614 can be read via PWM or SMBus compatible interface. Selection of PWM output is done in
EEPROM configuration (factory default is SMBus). PWM output has two programmable formats, single and
dual data transmission, providing single wire reading of two temperatures (dual zone object or object and
ambient). The PWM period is derived from the on-chip oscillator and is programmable.
Config Register[5:4] PWM1 data PWM2 data Tmin,1 Tmax,1 Tmin,2 Tmax,2
00 Ta T
obj1
Ta
range
,L Ta
range
,H To
min
To
max
01 Ta T
obj2
Ta
range
,L Ta
range
,H To
min
To
max
11 T
obj1
T
obj2
To
min
To
max
To
min
To
max
10*
T
obj2
Undefined
To
min
To
max
N.A. N.A.
Note: Serial data functions (2-wire / PWM) are multiplexed with a thermal relay function (described in the
“Thermal relay” section).
* not recommended for extended PWM format operation
Figure 11: PWM timing
8.5.1 Single PWM format
In single PWM output mode the settings for PWM1 data only are used. The temperature reading can be
calculated from the signal timing as:
()
TminTminTmax
T
t
Tout +
⎥
⎦
⎤
⎢
⎣
⎡
−= *
2
2
,
where Tmin and Tmax are the corresponding rescale coefficients in EEPROM for the selected temperature
output (Ta, object temperature range is valid for both Tobj1 and Tobj2 as specified in the previous table) and
T is the PWM period. Tout is T
obj1
, T
obj2
or T
a
according to Config Register [5:4] settings.
3901090614 Page 20 of 42 Data Sheet
Rev 004 30/Jul2008