EVB90615 Datasheet, PDF (23/30 Pages) Melexis Microelectronic Systems – Infra Red Thermometer

MLX90615
Infra Red Thermometer
11.3 PWM output
With PWM output configuration MLX90615 can be read via single wire. Output is open drain NMOS (with a
weak pull-up, 300 kΩ typ). Therefore external pull-up is required for high level state on the line with longer
wires. Simple level shifting is possible with a single resistor. ESD protective clamp on the SDA pin consists of
4 diodes to Vdd, thus allowing high level to go up to 5V disregarding the MLX90615 supply voltage value.
C1
0.1uF
2
Vdd
1
SCL
SDA
3
U1
Vss
MLX90615
4
Vdd
R1
10k
MCU
PW M Capture
Vss
+3V
+Vdd2
C2
Figure 20: Using MLX90615 PWM output
In EEPROM two PWM periods can be programmed – 102.4 or 1 ms (typ). With remote installation (wires)
PWM is recommended as more robust to EMI than the SMBus and the high PWM period would be also
preferred. As a factory default, once PWM is enabled, output will cover 0…50°C object temperature range (as
12.5 … 62.5% duty cycle) at 1kHz frequency.
3901090615
Rev 001
Page 23 of 30
Data Sheet
28/Aug/2008