Data Sheet

MLX90614 family

Single and Dual Zone

Infra Red Thermometer in TO-39

8.4.2 Differences with the standard SMBus specification (reference [1])

There are eleven command protocols for standard SMBus interface. The MLX90614 supports only two of

them. Not supported commands are:

• Quick Command

• Byte commands - Sent Byte, Receive Byte, Write Byte and Read Byte

• Process Call

• Block commands – Block Write and Write-Block Read Process Call

Supported commands are:

• Read Word

• Write Word

8.4.3 Detailed description

The PWM/SDA pin of MLX90614 can operate also as PWM output, depending on the EEPROM settings. If

PWM is enabled, after POR the PWM/SDA pin is directly configured as PWM output. The PWM mode can be

avoided and the pin can be restored to its Data function by a special command. That is why hereafter both

modes are treated separately.

8.4.3.1 Bus Protocol

Figure 4: SMBus packet element key

1181 17 1

WrSlave Address A Data Byte

Slave-to-Master

Master-to-Slave

Packet Error Code

PEC

Stop Condition

Acknowledge (this bit can be 0 for ACK and 1 for NACK)

Write (bit value of 0)

Read (bit value of 1)

Repeated Start ConditionSr

Start Condition

After every 8 bits received by the SD an ACK/NACK takes place. When a MD initiates communication, it first

sends the address of the slave and only the SD which recognizes the address will ACK, the rest will remain

silent. In case the SD NACKs one of the bytes, the MD should stop the communication and repeat the

message. A NACK could be received after the PEC. This means that there is an error in the received

message and the MD should try sending the message again. The PEC calculation includes all bits except the

3901090614 Page 15 of 42 Data Sheet

Rev 004 30/Jul2008