Datasheet

MAX34451 PMBus 16-Channel V/I Monitor and
12-Channel Sequencer/Marginer
www.maximintegrated.com
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OPERATION (01h)
The OPERATION command is used to turn the power
supply on and off in conjunction with the CONTROLn
input pin. The OPERATION command is also used to
cause the power supply to set the output voltage to the
upper or lower margin voltages. The power supply stays
in the commanded operating mode until a subsequent
OPERATIONcommandora change in thestateofthe
CONTROLn pin (if enabled) instructs the power sup-
ply to change to another state. The valid OPERATION
command byte values are shown in Table 10. The
OPERATIONcommandcontrolshowthedeviceresponds
whencommandedtochangetheoutput.Whenthecom-
mandbyteis00h,thedeviceimmediatelyturnsthepower
supply off and ignores any programmed turn-off delay.
Whenthecommandbyteissetto40h,41h,or42hthe
device powers down, according to the programmed turn-
offdelay.InTable10,Table11,andTable12,“actonany
fault”meansthatifanywarningorfaultontheselected
power supply is detected when the output is margined,
the device treats this as a warning or fault and responds
asprogrammed.“Ignoreall faults” meansthatallwarn-
ings and faults on the selected power supply are ignored.
Any command value not shown in these tables is an
invalid command. If the device receives a data byte that is
not listed in these tables, then it treats this as invalid data,
declaresadatafault(setsCMLbitandassertsALERT),
and responds as described in the Fault Management and
Reporting section.
In most cases, for power-on and power-off control, the
OPERATIONcommandshouldbesentwhenthePAGE
issetto255.IfthePAGEissetto0–11,theOPERATION
command is only applied to the power supply on that
page and the power supply is turned on and off using the
associated TON_DELAY and TOFF_DELAY settings
without any regard to the other supplies.
Forindividualchannel-marginingcontrol,theOPERATION
commandcanbeusedwiththePAGEsetto0–11.When
the PAGE is set to 255, the OPERATION margining
commands affect all channels.
TheOPERATIONcommandforthedevicecontainsafew
specialvaluesthatarenotpartofthePMBusstandard
toallowthedevicetoofferindependentcontrol.Seethe
shaded values in Table 11.
Table 10. OPERATION (01h) Command Byte with PAGE = 0–11
(When Bit 3 of ON_OFF_CONFIG = 1)
Note: All enabled channels must exceed POWER_GOOD_ON for margining to begin.
COMMAND BYTE POWER SUPPLY ON/OFF MARGIN STATE
00h
Immediateoff(nosequencing) —
40h
Soft-off(withsequencing) —
80h On Margin off
94h On
Marginlow(ignoreallfaults)
98h On Marginlow(actonanyfault)
A4h On Marginhigh(ignoreallfaults)
A8h On Marginhigh(actonanyfault)