Data Sheet

MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
11.3 PWM output operation
Using the PWM output mode of the MLX90614 is very simple, as shown on Figure 25.
J1
CON1
PWM
Vdd
GND
2
0.1uF
Vdd
U1
MLX90614
Vss
PWM
SDA
1
C1
SCL
Vz
3
Figure 25: Connection of MLX90614 for PWM output mode
The PWM mode is free-running after POR when configured in EEPROM. The SCL pin must be forced high
(can be shorted to Vdd pin) for PWM mode operation.
A pull-up resistor can be used to preserve the option for SMBus operation while having PWM as a default as
is shown on Figure 26.
PWM
SDA
10k
3
1
Vdd
2
R1
SCL
Vz
J1
CON1
SCL
PWM/SDA
GND
Vdd
U1
MLX90614
Vss
0.1uF
C1
Figure 26: PWM output with SMBus available
Again, the PWM mode needs to be written as the POR default in EEPROM. Then for PWM operation the
SCL line can be high impedance, forced high, or even not connected. The pull-up resistor R1 will ensure
there is a high level on the SCL pin and the PWM POR default will be active. SMBus is still available (for
example – for further reconfiguration of the MLX90614, or sleep mode power management) as there are pull-
up resistors on the SMBus lines anyway.
PWM can be configured as open drain NMOS or a push-pull output. In the case of open drain external pull-up
will be needed. This allows cheap level conversion to lower logic high voltage. Internal pull-ups present in
many MCUs can also be used.
11.4 Thermal alert / thermostat
U2
AC line
R1
3
C2
10uF
C1
0.1uF
U1 MCU
SCL
SDA
GND
Vdd
2
SCL
Vz
C*
2
SCL
Vz
U1
MLX90614Axx
U1
MLX90614Bxx
Vss
Vdd
11
SMBus
R2
Vdd
4
Q1
4
1
+5V
U1
MLX90614Axx
Vdd
Vss
+3.3V R1
C3
0.1uF
SCL
Vz
3
R2
+24V
Vss
C1
0.1uF
PWM
SDA
PWM
SDA
3
4
PWM
SDA
D1
Alert dev ice
+
-
2
Figure 27: Thermal alert/thermostat applications of MLX90614
The MLX90614 can be configured in EEPROM to operate as a thermal relay. A non contact freezing or
boiling prevention with 1 mA quiescent current can be built with two components only – the MLX90614 and a
3901090614 Page 33 of 42 Data Sheet
Rev 004 30/Jul2008