MLX90614_15 Datasheet, PDF(15/51 Page) Melexis Microelectronic Systems – Single and Dual Zone Infra Red Thermometer in TO-39

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MLX90614_15 Datasheet, PDF (15/51 Pages) Melexis Microelectronic Systems – Single and Dual Zone Infra Red Thermometer in TO-39

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MLX90614 family

Single and Dual Zone

Infra Red Thermometer in TO-39

Note*: This address is readable and writable. Bit 3 should not be altered as this will cancel the factory

calibration.

Note**: EEPROM error signaling is implemented in automotive grade parts only.

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:

â¢ Quick Command

â¢ Byte commands - Sent Byte, Receive Byte, Write Byte and Read Byte

â¢ Process Call

â¢ Block commands â Block Write and Write-Block Read Process Call

Supported commands are:

â¢ Read Word

â¢ 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. Even if the

device is in PWM mode SMBus communication may be restored by a special command. That is why hereafter

both modes are treated separately.

8.4.3.1 Bus Protocol

S Slave Address Wr A

Data Byte

Start Condition

Repeated Start Condition

Rd Read (bit value of 1)

Wr Write (bit value of 0)

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

Stop Condition

PEC Packet Error Code

Master-to-Slave

Slave-to-Master

Figure 4: SMBus packet element key

After every received 8 bits the SD should issue ACK or NACK. 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 START,

3901090614

Rev 009

Page 15 of 52

Data Sheet

June 29, 2015

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