ADM1276-3ACPZ-RL(Rev0) View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

ADM1276-3ACPZ-RL
(Rev.:Rev0)

Hot Swap Controller and Digital Power and Energy Monitoring with PMBus Interface

Analog Devices 

ADM1276

A group command differs from a nongroup command in that

It is possible to determine at any time whether the hot swap output

after the data is written to one slave device, a repeated start

is enabled using the STATUS_BYTE or the STATUS_WORD

condition is placed on the bus followed by the address of the

command (see the Status Commands section).

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 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.

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.

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.

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.

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.

HOT SWAP CONTROL COMMANDS

POWER_CYCLE Command

OPERATION Command

The POWER_CYCLE command can be used to request that the

The GATE pin that drives the FET is controlled by a dedicated

ADM1276 be turned off for ~4 seconds and then turned back on.

hot swap state machine. The UV and OV input pins, the TIMER

This command can be useful if the processor that controls the

and SS pins, and the current sense all feed into the state machine

ADM1276 is also powered off when the ADM1276 is turned off.

and they control when and how strongly the gate is turned off.

This command allows the processor to request that the ADM1276

It is also possible to control the hot swap GATE output using

turn off and on again as part of a single command.

commands over the PMBus interface. The OPERATION

ADM1276 INFORMATION COMMANDS

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.

CAPABILITY Command

The CAPABILITY command can be used by host processors

to determine the I2C bus features that are supported by the

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

If the on bit is never changed, the UV input or the ENABLE

The MFR_ID, MFR_MODEL, and MFR_REVISION commands

input is the hot swap master on/off control signal.

return ASCII strings that can be used to facilitate detection and

By default at power-up, the OPERATION command is disabled

identification of the ADM1276 on the bus.

and must be enabled using the DEVICE_CONFIG command.

This prevents inadvertent shutdowns of the hot swap controller

These commands are read using the SMBus block read message

type. This message type requires that the ADM1276 return a

by software.

byte count corresponding to the length of the string data that is

If the on bit is set to 0 while the UV signal is high, the hot swap

to be read back.

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.

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

Rev. 0 | Page 27 of 48

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