MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
8.6 Switching Between PWM and SMBus communication
8.6.1 PWM is enabled
The diagram below illustrates the way of switching to SMBus if PWM is enabled (factory programmed POR
default for MLX90614 is SMBus, PWM disabled). Note that the SCL pin needs to be kept high in order to use
PWM.
tREQ
SCL
PWM/SDA
Start
Stop
PWM
SMBus
Figure 13: Switching from PWM mode to SMBus
8.6.2 Request condition
tREQ
SCL
SMBus Request
Figure 14: Request (switch to SMBus) condition
If PWM is enabled, the MLX90614’s SMBus Request condition is needed to disable PWM and reconfigure
PWM/SDA pin before starting SMBus communication. Once PWM is disabled, it can be only enabled by
switching the supply Off-On or exit from Sleep Mode. The MLX90614’s SMBus request condition requires
forcing LOW the SCL pin for period longer than the request time (tREQ). The SDA line value is ignored in this
case.
8.6.3 PWM is disabled
If PWM is disabled by means of EEPROM the PWM/SDA pin is directly used for the SMBus purposes after
POR. Request condition should not be sent in this case.
3901090614
Rev 003
Page 21 of 40
Data Sheet
03/Oct/2007
MELEXIS [ Melexis Microelectronic Systems ]
