EVAL-ADM1276EBZ Analog Devices, EVAL-ADM1276EBZ Datasheet - Page 27

• Manufacturer Part Number: EVAL-ADM1276EBZ
• Description: Power Management IC Development Tools EVALUATION BOARD
• Manufacturer: Analog Devices
• Type: Hot Swap & Power Distributionr
• Series: ADM1276r

Specifications of EVAL-ADM1276EBZ

• Rohs: yes
• Tool Is For Evaluation Of: ADM1276
• Input Voltage: 20 V
• Factory Pack Quantity: 1

Data Sheet
A group command differs from a nongroup command in that
after the data is written to one slave device, a repeated start
condition is placed on the bus followed by the address of the
next slave device and data. This continues until all of the
devices have been written to, at which point the stop condition
is placed on the bus by the master device.
The format of a group command and a group command with
PEC is shown in Figure 59 and Figure 60.
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 simultaneously. In the case of
the ADM1276, it is also possible to issue a power monitor
command that initiates a conversion, causing multiple ADM1276
devices to sample together at the same time.
HOT SWAP CONTROL COMMANDS
OPERATION Command
The GATE pin that drives the FET is controlled by a dedicated
hot swap state machine. The UV and OV input pins, the TIMER
and SS pins, and the current sense all feed into the state machine
and they control when and how strongly the gate is turned off.
It is also possible to control the hot swap GATE output using
commands over the PMBus interface. The OPERATION
command can be used to request the hot swap output to turn
on. However, if the UV pin indicates that the input supply is less
than required, the hot swap output is not turned on, even if the
OPERATION command indicates that the output should be
enabled.
If the OPERATION command is used to disable the hot swap
output, the GATE pin is held low, even if all hot swap state
machine control inputs indicate that it can be enabled.
The default state of Bit 7 (also named the on bit) of the
OPERATION command is 1; therefore, the hot swap output
is always enabled when the ADM1276 emerges from UVLO.
If the on bit is never changed, the UV input or the ENABLE
input is the hot swap master on/off control signal.
By default at power-up, the OPERATION command is disabled
and must be enabled using the DEVICE_CONFIG command.
This prevents inadvertent shutdowns of the hot swap controller
by software.
If the on bit is set to 0 while the UV signal is high, the hot swap
output is turned off. If the UV signal is low or if the OV signal
is high, the hot swap output is already off and the status of the
on bit has no effect.
If the on bit is set to 1, the hot swap output is requested to turn
on. If the UV signal is low or if the OV signal is high, setting the
on bit to 1 has no effect, and the hot swap output remains off.
Rev. B | Page 27 of 48
DEVICE_CONFIG Command
The DEVICE_CONFIG command configures certain settings
within the ADM1276, for example, enabling or disabling foldback
in the hot swap controller, or modifying the duration of the
severe overcurrent glitch filter. This command is also used to
configure the polarity of the second IOUT current warnings.
The OPERATION command is disabled at power-up. If the
OPERATION command is received, the ADM1276 responds
with a no acknowledge. To allow use of the OPERATION
command, the OPERATION_CMD_EN bit must be set via
the DEVICE_CONFIG command.
POWER_CYCLE Command
The POWER_CYCLE command can be used to request that the
ADM1276 be turned off for ~4 seconds and then turned back on.
This command can be useful if the processor that controls the
ADM1276 is also powered off when the ADM1276 is turned off.
This command allows the processor to request that the ADM1276
turn off and on again as part of a single command.
ADM1276 INFORMATION COMMANDS
CAPABILITY Command
The CAPABILITY command can be used by host processors
to determine the I
ADM1276. The features that can be reported include the max-
imum bus speed, whether the device supports the packet error
checking (PEC) byte, and the SMBAlert reporting function.
PMBUS_REVISION Command
The PMBUS_REVISION command reports the version of Part I
and Part II of the PMBus standard.
MFR_ID, MFR_MODEL, and MFR_REVISION Commands
The MFR_ID, MFR_MODEL, and MFR_REVISION commands
return ASCII strings that can be used to facilitate detection and
identification of the ADM1276 on the bus.
These commands are read using the SMBus block read message
type. This message type requires that the ADM1276 return a
byte count corresponding to the length of the string data that is
to be read back.
STATUS COMMANDS
The ADM1276 provides a number of status bits that are used
to report faults and warnings from the hot swap controller and
the power monitor. These status bits are located in six different
registers that are arranged in a hierarchy. The STATUS_BYTE
and STATUS_WORD commands provide 8 bits and 16 bits of
high level information, respectively. The STATUS_BYTE and
STATUS_WORD commands contain the most important status
It is possible to determine at any time whether the hot swap output
is enabled using the STATUS_BYTE or the STATUS_WORD
command (see the Status Commands section).
The OPERATION command can also clear any latched faults in
the status registers. To clear latched faults, set the on bit to 0 and
then reset it to 1.
2
C bus features that are supported by the
ADM1276