MLX90614 datasheet(21/40 Pages) ETC2

21 / 40 page

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.

SCL

PWM/SDA

Start

Stop

REQ

PWM

SMBus

Figure 13: Switching from PWM mode to SMBus

8.6.2 Request condition

SCL

SMBus Request

REQ

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

Page 21 of 40

Data Sheet

Rev 003

03/Oct/2007

MLX90614 Datasheet(PDF) 21 Page - List of Unclassifed Manufacturers