Datasheet

Data Sheet ADP1053
Rev. A | Page 35 of 84
Command Overview
DATA TRANSFER
Data transfer using the PMBus slave is established using PMBus
commands. The PMBus specification requires that all PMBus
commands start with a slave address with the R/
W
bit cleared
(set to 0), followed by the command code. All PMBus commands
supported by the follow one of the protocol types
shown in through .
ADP1053
Figure 31 Figure 37
Format Overview
The PMBus slave follows the transfer protocol of the SMBus
specification, which is based on the fundamental transfer
protocol format of the Philips I
2
C Bus Specification, dated
January 2000. Data transfers are byte wide, lower byte first.
Each byte is transmitted serially, most significant bit (MSB)
first. A typical transfer is diagrammed in Figure 30. See the
SMBus and I
2
C specifications for an in-depth discussion of
the transfer protocols.
MASTER TO SLAVE
SLAVE TO MASTER
SAAW
7-BIT SLAVE
ADDRESS
8-BIT DATA P
10241-135
The ADP1053 also supports manufacturer-specific extended
commands. These commands follow the same protocol as the
standard PMBus commands. However, the command code
consists of two bytes that range from 0xFE00 to 0xFFFF.
Using the manufacturer-specific extended commands, the PMBus
device manufacturer can add an additional 256 manufacturer-
specific commands to its PMBus command set.
Figure 30. Basic Data Transfer
Figure 30 through Figure 37 use the following abbreviations:
S = start condition
P = stop condition
Sr = repeated start condition
W
= write bit (0)
R = read bit (1)
A = acknowledge bit (0)
A
= not-acknowledge bit (1)
SPAAW7-BIT SLAVE ADDRESS COMMAND CODE
MASTER TO SLAVE
SLAVE TO MASTER
10241-038
Figure 31. Send Byte Protocol
ASPAADATA BYTEW
7-BIT SLAVE
ADDRESS
COMMAND
CODE
MASTER TO SLAVE
SLAVE TO MASTER
10241-039
Figure 32. Write Byte Protocol
AA
COMMAND
CODE
AS P
DATA BYTE
LOW
W
7-BIT SLAVE
ADDRESS
A
DATA BYTE
HIGH
MASTER TO SLAVE
SLAVE TO MASTER
10241-138
Figure 33. Write Word Protocol
A
SAAW
7-BIT SLAVE
ADDRESS
COMMAND
CODE
PRDATA BYTE
Sr
A
7-BIT SLAVE
ADDRESS
MASTER TO SLAVE
SLAVE TO MASTER
10241-139
Figure 34. Read Byte Protocol
AA
S
AA
W
7-BIT SLAVE
ADDRESS
COMMAND
CODE
PRSr
7-BIT SLAVE
ADDRESS
MASTER TO SLAVE
SLAVE TO MASTER
DATA BYTE
LOW
DATA BYTE
HIGH
A
10241-140
Figure 35. Read Word Protocol