MAX6651 MAXIM [Maxim Integrated Products], MAX6651 Datasheet - Page 7

• Manufacturer Part Number: MAX6651
• Description: Fan-Speed Regulators and Monitors with SMBus/I2C-Compatible Interface
• Manufacturer: MAXIM [Maxim Integrated Products]

Figure 2a. SMBus Protocol: Write Byte Format
Figure 2b. SMBus Protocol: Read Byte Format
Figure 2c. SMBus Protocol: Receive Byte Format
S = Start condition
P = Stop condition
S
S
S
S
Slave Address
Slave Address
Slave Address.
Repeated due to
change in data-flow
direction
Slave Address
ADDRESS
ADDRESS
ADDRESS
ADDRESS
7 bits
7 bits
7 bits
7 bits
_______________________________________________________________________________________
Shaded = Slave transmission
ACK = Acknowledged = 0
A = Not acknowledged = 1
with SMBus/I
WR
WR
RD
RD
0
0
1
1
Fan-Speed Regulators and Monitors
ACK
ACK
ACK
ACK
Data byte: Reads from
the register set by the
command byte.
Command byte: Selects
which register you are
writing to.
Data byte: Reads data
from the register com-
manded by the last
read-byte or write-byte
transmission; also
used for SMBus alert
response return address.
Command byte: Selects
which register you are
reading from.
COMMAND
COMMAND
WR = Write = 0
RD = Read =1
DATA
DATA
8 bits
8 bits
8 bits
8 bits
2
C-Compatible Interface
ACK
ACK
A
A
Data byte: Data goes into
the register set by the
command byte (to set
thresholds, configuration
masks, and sampling rate).
P
P
DATA
8 bits
ACK
P
7