Datasheet

6-Channel Intelligent Fan Controller
MAX31785
16
Address Select
On device power-up, the device samples the A0 and A1
pins to determine the PMBus/SMBus serial-port address.
SMBus/PMBus Operation
The device implements the PMBus command structure
using the SMBus format. The structure of the data flow
between the host and the slave is shown below for sev-
eral different types of transactions. Data is sent most
significant bit (MSB) first.
Table 2. PMBus/SMBus Serial-Port
Address
SMBus/PMBus Communication Examples
KEY:
S = START
Sr = REPEATED START
P = STOP
W = WRITE BIT (0)
R = READ BIT (1)
A = ACKNOWLEDGE (0)
NA = NOT ACKNOWLEDGE (1)
SHADED BLOCK = SLAVE TRANSACTION
READ WORD FORMAT
1 7 1 1 8 1 1 7 1 1 8 1 8 1 1
S
SLAVE
ADDRESS
W A
COMMAND
CODE
A Sr
SLAVE
ADDRESS
R A
DATA BYTE
LOW
A
DATA BYTE
HIGH
NA P
READ BYTE FORMAT
1 7 1 1 8 1 1 7 1 1 8 1 1
S
SLAVE
ADDRESS
W A
COMMAND
CODE
A Sr
SLAVE
ADDRESS
R A DATA BYTE NA P
WRITE WORD FORMAT
1 7 1 1 8 1 8 1 8 1 1
S
SLAVE
ADDRESS
W A
COMMAND
CODE
A
DATA BYTE
LOW
A
DATA BYTE
HIGH
A P
WRITE BYTE FORMAT
1 7 1 1 8 1 8 1 1
S
SLAVE
ADDRESS
W A
COMMAND
CODE
A DATA BYTE A P
SEND BYTE FORMAT
1 7 1 1 8 1 1
S
SLAVE
ADDRESS
W A
COMMAND
CODE
A P
A1 A0
7-BIT SLAVE
ADDRESS
100kI to V
SS
100kI to V
SS
1010 010 (A4h)
100kI to V
DD
1010 011 (A6h)
100kI to V
DD
100kI to V
SS
1010 100 (A8h)
100kI to V
DD
1010 101 (AAh)