MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
11 Applications Information
11.1 Use of the MLX90614 thermometer in SMBus configuration
+3.3V
R1 R2
U1
Vdd
MCU
2
PWM
SDA
SDA
SCL
GND
SMBus
1
SCL
Vz
Vdd
3
Vss
4
U2
C1
MLX90614Bxx
0.1uF
Figure 22: MLX90614 SMBus connection
Connection of the MLX90614 to SMBus with 3.3V power supply. The MLX90614 has diode clamps SDA/SCL
to Vdd so it is necessary to provide MLX90614 with power in order not to load the SMBus lines.
11.2 Use of multiple MLX90614s in SMBus configuration
+3.3V
I1
I2
R1
R2
U1
Vdd
MCU
Ipu1
Ipu2
2
PWM
SDA
SDA
SCL
GND
SMBus
1
SCL
Vz
Vdd
3
Current source or resistor
pull-ups of the bus
Vss
4
U1
C1
MLX90614Bxx
0.1uF
C3
2
Cbus1
PWM
SDA
1
SCL
Vz
Vdd
3
Cbus2
C4
Vss
4
U1
C2
MLX90614Bxx
0.1uF
SDA SCL
Figure 23: Use of multiple MLX90614 devices in SMBus network
The MLX90614 supports a 7-bit slave address in EEPROM, thus allowing up to 127 devices to be read via
two common wires. With the MLX90614BBx this results in 254 object temperatures measured remotely and
an additional 127 ambient temperatures which are also available. Current source pull-ups may be preferred
with higher capacitive loading on the bus (C3 and C4 represent the lines’ parasitics), while simple resistive
pull-ups provide the obvious low cost advantage.
3901090614
Rev 003
Page 30 of 40
Data Sheet
03/Oct/2007
MELEXIS [ Melexis Microelectronic Systems ]
