Intel LF80550KF0604M Data Sheet

Dual-Core Intel® Xeon® Processor 7100 Series Datasheet

111

The thermal sensor responds to five of the SMBus packet types: Write Byte, Read Byte, 
Send Byte, Receive Byte, and Alert Response Address (ARA). The Send Byte packet can 
be used for sending one-shot commands. The Receive Byte packet accesses the 
register commanded by the last Read Byte packet and can be used to continuously read 
from a register. If a Receive Byte packet was preceded by a Write Byte or send Byte 
packet more recently than a Read Byte packet, then the behavior is undefined. 

 through 

 diagram the five packet types. In these figures, ‘S’ 

represents the SMBus start bit, ‘P’ represents a stop bit, ‘Ack’ represents an 
acknowledge, and ‘///’ represents a negative acknowledge (NACK). The shaded bits are 
transmitted by the thermal sensor, and the bits that aren’t shaded are transmitted by 
the SMBus host controller.

1.

This is an 8-bit field. The device which sent the alert will respond to the ARA Packet with its address in the 

seven most significant bits. The least significant bit is undefined and may return as a ‘1’ or ‘0’. See 

 for details on the Thermal Sensor Device addressing.

2.

The shaded bits are transmitted by the thermal sensor, and the bits that aren’t shaded are transmitted by 

the SMBus host controller.

1

7-bits

0

1

8-bits

1

8-bits

1

1

1

7-bits

0

1

8-bits

1

1

7-bits

1

1

8-

bits

1

1

1

7-bits

0

1

8-bits

1

1

1

7-bits

1

1

8-bits

1

1

1

0001 100

1

1

Device Address

1

1

1