ADM1075 datasheet(32/52 Pages) AD

32 / 52 page

ADM1075

Data Sheet

Rev. A | Page 32 of 52

All warnings in the ADM1075 are generated by the power

monitor sampling voltage and current and then comparing

these measurements to the threshold values set by the various

limit commands. A warning has no effect on the hot swap

controller, but it may generate an SMBAlert on one or both of

the GPOx/ALERTx output pins.

When a fault or warning status bit is set, it always means that the

status condition—fault or warning—is active or was active at

some point in the past. When a fault or warning bit is set, it is

latched until it is explicitly cleared using either the OPERATION

or the CLEAR_FAULTS command. Some other status bits are

live, that is, they always reflect a status condition and are never

latched.

STATUS_BYTE and STATUS_WORD Commands

The STATUS_BYTE and STATUS_WORD commands can

be used to obtain a snapshot of the overall part status. These

commands indicate whether it is necessary to read more

detailed information using the other status commands.

The low byte of the word returned by the STATUS_WORD

command is the same byte returned by the STATUS_BYTE

command. The high byte of the word returned by the STATUS_

WORD command provides a number of bits that can be used to

determine which of the other status commands must be issued

to obtain all active status bits.

STATUS_INPUT Command

The STATUS_INPUT command returns a number of bits

relating to voltage faults and warnings and power warnings on

the input supply.

STATUS_IOUT Command

The STATUS_IOUT command returns a number of bits

relating to current faults and warnings on the output supply.

STATUS_VAUX Command

The STATUS_VAUX command returns a number of bits

relating to current faults and warnings on the output supply.

STATUS_MFR_SPECIFIC Command

The STATUS_MFR_SPECIFIC command is a standard PMBus

command, but the contents of the byte returned is specific to

the ADM1075.

CLEAR_FAULTS Command

The CLEAR_FAULTS command is used to clear fault and

warnings bits when they are set. Fault and warnings bits are

latched when they are set. In this way, a host can read the bits

any time after the fault or warning condition occurs and

determine which problem actually occurred.

If the CLEAR_FAULTS command is issued and the fault or warn-

ing condition is no longer active, the status bit is cleared. If the

condition is still active—for example, if an input voltage is below

the undervoltage threshold of the UV pin—the CLEAR_FAULTS

command attempts to clear the status bit, but that status bit is

immediately set again.

GPO AND ALERT PIN SETUP COMMANDS

Two multipurpose pins are provided on the ADM1075:

GPO1/ALERT1/CONV and GPO2/ALERT2.

The GPO1/ALERT1/CONV and GPO2/ALERT2 pins have

two output modes of operation. These pins can be configured

independently over the PMBus as general-purpose digital

outputs. They can both be configured to generate an SMBAlert

when one or more fault/warning status bits become active in the

PMBus status registers. For an example of how to configure these

pins to generate an SMBAlert and how to respond and clear the

condition, see the

section.

Example Use of SMBus Alert Response

Address

The GPO1/ALERT1/CONV pin can also be configured as an

input (CONV) to drive the power monitor in single-shot run

mode and to control when a power monitor ADC sampling

cycle begins. This function can be used to synchronize sampling

across multiple

devices, if required.

ADM1075

ALERT1_CONFIG and ALERT2_CONFIG Commands

Using combinations of bit masks, the ALERT1_CONFIG and

ALERT2_CONFIG commands can be used to select the status

bits that, when set, generate an SMBAlert signal to a processor.

They can also be used to set a GPO mode on the pin, so that it

is under software control. If this mode is set, the SMBAlert

masking bits are ignored.

On the ADM1075, one of the inputs can also be configured

as a hardware-based convert control signal. If this mode is set,

the GPO and SMBAlert masking bits are ignored.

POWER MONITOR COMMANDS

The ADM1075 provides a high accuracy, 12-bit current and

voltage power monitor. The power monitor can be configured

in a number of different modes of operation and can run in

either continuous mode or single-shot mode with a number

of different sample averaging options.

The power monitor can measure the following:

•

Input voltage (VIN)

•

Output current (IOUT)

•

Auxiliary voltage (VAUX)

The following quantities are then calculated:

•

Input power (PIN)

•

Input energy (EIN)

PMON_CONFIG Command

The power monitor can run in a number of different modes with

different input voltage range settings. The PMON_CONFIG

command is used to set up the power monitor.

ADM1075 Datasheet(PDF) 32 Page - Analog Devices

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