adm1075-2aruz-rl7 Analog Devices, Inc., adm1075-2aruz-rl7 Datasheet - Page 30

• Manufacturer Part Number: adm1075-2aruz-rl7
• Description: −48 V Hot Swap Controller And Digital Power Monitor With Pmbus Interface
• Manufacturer: Analog Devices, Inc.

ADM1075
GROUP COMMANDS
The PMBus standard defines what are known as group
commands. Group commands are single bus transactions that
send commands or data to more than one device at the same
time. Each device is addressed separately, using its own address;
there is no special group command address. A group command
transaction can contain only write commands that send data to
a device. It is not possible to use a group command to read data
from devices.
From an I
consists of the following:
•
•
•
•
Sr
Sr
S
I
Slave address bits and a write bit (followed by ACK from
the slave device)
One or more data bytes (each of which is followed by ACK
from the slave device)
I
MASTER TO SLAVE
SLAVE TO MASTER
2
2
C start condition
C stop condition to end the transaction
DEVICE N ADDRESS
DEVICE 1 ADDRESS
DEVICE 2 ADDRESS
2
C protocol point of view, a normal write command
Sr
Sr
S
S
S
MASTER TO SLAVE
SLAVE TO MASTER
MASTER TO SLAVE
SLAVE TO MASTER
DATA BYTE 1
DATA BYTE 1
DEVICE N ADDRESS
DEVICE 1 ADDRESS
DEVICE 2 ADDRESS
SLAVE ADDRESS
SLAVE ADDRESS
W
W
W
A
A
A
COMMAND CODE N
COMMAND CODE 1
COMMAND CODE 2
A
A
W
W
W
W
W
A
A
A
A
A
DATA BYTE 2
DATA BYTE 2
COMMAND CODE N
COMMAND CODE 1
COMMAND CODE 2
COMMAND CODE
COMMAND CODE
Figure 60. Block Read and Block Read with PEC
A
A
A
Figure 62. Group Command with PEC
Figure 61. Group Command
LOW DATA BYTE
LOW DATA BYTE
LOW DATA BYTE
A
A
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A
A
A
A
A
Sr
Sr
ONE OR MORE DATA BYTES
ONE OR MORE DATA BYTES
ONE OR MORE DATA BYTES
LOW DATA BYTE
LOW DATA BYTE
LOW DATA BYTE
DATA BYTE N
DATA BYTE N
SLAVE ADDRESS
SLAVE ADDRESS
A group command differs from a nongroup command in that,
after the data is written to one slave device, a repeated start
condition is put on the bus followed by the address of the next
slave device and data. This continues until all the devices have
been written to, at which point the stop condition is put on the
bus by the master device.
The format of a group command and a group command with
PEC is shown in Figure 62.
Each device that is written to as part of the group command
does not immediately execute the command written. The device
must wait until the stop condition appears on the bus. At that
point, all devices execute their commands at the same time.
Using a group command, it is possible, for example, to turn
multiple PMBus devices on or off at the same time. In the case
of the ADM1075, it is also possible to issue a power monitor
command that initiates a conversion, causing multiple
devices to sample together at the same time. This is analogous
to connecting the GPO1/ ALERT1 /CONV pins together and
configuring the pin in the convert (CONV) mode to drive the
power monitor sampling.
A
A
A
ONE OR MORE DATA BYTES
ONE OR MORE DATA BYTES
ONE OR MORE DATA BYTES
HIGH DATA BYTE
HIGH DATA BYTE
HIGH DATA BYTE
A
A
A
A
A
R
R
P
A
A
HIGH DATA BYTE
HIGH DATA BYTE
HIGH DATA BYTE
BYTE COUNT = N
BYTE COUNT = N
PEC
A
A
A
A
P
PEC N
PEC 1
PEC 2
A
A
A
A
A
P
Data Sheet
ADM1075
A
A
A
P