Datasheet

MAX34451 PMBus 16-Channel V/I Monitor and
12-Channel Sequencer/Marginer
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MFR_FAULT_RESPONSE (D9h)
The MFR_FAULT_RESPONSE command specifies the
response to each fault or warning condition support-
ed by the device. In response to a fault/warning, the
devicealwaysreportsthefault/warningintheappropriate
status register and asserts the ALERT output (if enabled
in MFR_MODE).A CMLfault cannot cause any device
action other than setting the status bit and asserting the
ALERT
output.TheMFR_FAULT_RESPONSEcommand
isdescribedinTable30andshowninFigure10.
For each fault type (overvoltage or overcurrent, under-
voltage, sequencing error, and overtemperature), each
channel can be independently configured to respond in
therequiredmannerwiththeRESPONSEbitsinMFR_
FAULT_RESPONSE.Ifchannels0–11areconfiguredto
latch off for a particular fault, the channel turns off (either
immediatelyoraftertheTOFF_DELAYasconfiguredor
commanded)andalsoassertoneormoreoftheFAULTn
pinsiftheyareenabledwithbits18:16inMFR_FAULT_
RESPONSE.Thechannel remains off and the FAULTn
outputs remain asserted until either the master power
control is toggled using the OPERATION command or
CONTROLnpinsasconfiguredintheON_OFF_CONFIG
commandorthedeviceisresetorpowercycled.When
the device attempts to sequence the power supplies on,
all enabled faults must be cleared before the channel is
allowed to power-on or the FAULTn pins deasserted. If
channels12–15areconfiguredtolatchoff,theyrespond
likechannels0–11;however,allthepowersuppliesmust
be turned off before they are allowed to turn back on.
If the channel is configured to retry for a particular fault,
the channel turns off (either immediately or after the
TOFF_DELAY as configured or commanded) and also
assert one or more the FAULTn pins if they are enabled
withbits18:16inMFR_FAULT_RESPONSE.Thechan-
nel remains off and the FAULTn outputs remain asserted
forthetimeconfiguredinMFR_FAULT_RETRY.Afterthe
timeinMFR_FAULT_RETRYexpires,thedeviceattempts
to sequence the power supplies back on as long as all
the enabled faults in the channel are cleared. If all the
enabled faults are cleared, then the device deasserts
all the FAULTn pins it asserted and as long as no other
channels have asserted the FAULTn pins it has been
configured to monitor with bits 26:24 in MFR_FAULT_
RESPONSE,thepower-upsequencingbegins.
GlobalchannelsmustassertaFAULTn pin and respond
to that FAULTn pin for the channel to shut down.
LOCAL vs. GLOBAL Channels
With the MFR_FAULT_RESPONSE command (bit 14),
each power-supply channel can be tagged as either being
LOCALorGLOBAL.Whenbit14iscleared,thechannel
is configured as a LOCAL channel, which means that a
detected fault only affects this channel (or page). With
the RESPONSE bits in the MFR_FAULT_RESPONSE
command, the device can be configured to respond differ-
entlytoeachpossiblefault.Whenbit14isset,thechannel
is configured as a GLOBAL channel which means that
a detected fault on this channel can assert all enabled
FAULTn outputs. The FAULTn outputs that are enabled are
selectedwithbits18:16.OnlyGLOBALchannelsrespond
to FAULTn pins that are asserted. The FAULTn pins that
the channel should respond to are assigned with bits
26:24.LOCALchannelsdonotrespondtothefaultpins.
GLOBAL Channels Respond to FAULTn Assertion
Bits 26:24 in the MFR_FAULT_RESPONSE command
are used toconfigure GLOBALchannels to respond or
ignore one or more of the FAULTn pins when they are
asserted. When one or more of the enabled FAULTn
pinsisasserted,thechanneleitherdeassertsthePSENn
outputimmediatelyoraftertheTOFF_DELAYaccording
to the configuration of bit 0 in the ON_OFF_CONFIG
command.ThechannelcontinuestodeassertthePSENn
output until all enabled FAULTnpinsdeassert.Whenall
enabled FAULTn pins deassert, the channel sequences
on as configured if no channel faults are present.
Temperature Fault Response
A temperature fault is declared when any of the enabled
temperature sensors detect a fault. A temperature fault
actsgloballyandcanaffectallofthepowersupplies.For
all global supplies, the worst-case fault response of all
global channels is applied. If this response is latchoff or
retry, all FAULTn pins that are programmed to be asserted
by any of the global channels will be asserted. All local
channels respond independently, as programmed in that
channel’sMFR_FAULT_RESPONSE.