MLX90614_15 Datasheet, PDF (39/51 Pages) Melexis Microelectronic Systems – Single and Dual Zone Infra Red Thermometer in TO-39

11 Applications Information
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
11.1 Use of the MLX90614 thermometer in SMBus configuration
+3.3V
R1 R2
2
PWM
SD A
Vdd
3
SCL ¹
Vz
C1 U2
0.1uF
Vss
4 ^MLX90614Bxx
SMBus
U1
Vdd
SDA
SCL
GND
MCU
Figure 35: MLX90614 SMBus connection
Figure 35 shows the connection of a MLX90614 to a 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
2
PWM
SD A
Vdd
3
SCL ¹
Vz
C1 U1
0.1uF
V ss
4 ^MLX90614Bxx
Ipu1
Ipu2
Current source or resistor
pull-ups of the bus
R2
SMBus
U1
Vdd
SDA
SCL
GND
MCU
2
PWM
SD A
Vdd
3
SCL ¹
Vz
C2 U1
0.1uF
V ss
4 ^MLX90614Bxx
C3
Cbus1
Cbus2
C4
SDA SCL
Figure 36: 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 MLX90614xBx 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’ parasitic), while simple resistive pull-ups
provide the obvious low cost advantage.
3901090614
Rev 009
Page 39 of 52
Data Sheet
June 29, 2015