Datasheet

MAX34451 PMBus 16-Channel V/I Monitor and
12-Channel Sequencer/Marginer
www.maximintegrated.com
Maxim Integrated │ 32
Table 14. WRITE_PROTECT (10h) Command Byte
Table 15. Memory Transfer PMBus Commands
Note: No fault or error is generated if the host attempts to write to a protected area.
Figure 6. Device Configuration Data Management
CLEAR_FAULTS (03h)
The CLEAR_FAULTS command is used to clear any
latched fault or warning bits in the status registers that
have been set and also unconditionally deasserts the
ALERT output. This command clears all bits simultane-
ously. The CLEAR_FAULTS command does not cause
a power supply that has latched off for a fault condition
to restart. The state of the PSENn outputs under fault
conditions are not affected by this command and changes
onlyif commanded through the OPERATIONcommand
ortheCONTROLnpins.Ifafaultisstillpresentafterthe
CLEAR_FAULTScommandisexecuted,thefaultstatus
bit is immediately set again, but ALERT is not reasserted.
ALERT is only asserted again when a new fault or warn-
ing is detected that occurs after the CLEAR_FAULTS
command is executed. This command is write-only. There
is no data byte for this command.
WRITE_PROTECT (10h)
The WRITE_PROTECT command is used to provide
protection against accidental changes to the device’s oper-
ating memory. All supported commands can have their
parameters read, regardless of the WRITE_PROTECT
settings. The WRITE_PROTECT message content is
described in Table 14.
Device Conguration Data Management
The device stores configuration data in both nonvolatile
flash memory and volatile RAM. The PMBus engine
managesthedeviceconfigurationdata.SeeFigure6.
The flash memory has three separate arrays for
configurationparameters,whereastheRAMonly has a
singlearray.WhenaPMBuscommandiswrittentothe
device,itisalwayswrittentotheRAM.Whenthedevice
is shipped from the factory, the MAIN and BACKUP
flash memory arrays are identical and are configured as
shown in Table 3.
TheSINGLEarrayisempty.
ThereisasetoffivePMBuscommandsthatcanbeused
totransferdatabetweentheflashandRAMarrays.These
commands are described in Table 15.
COMMAND BYTE MEANING
80h
DisablesallwritesexcepttheWRITE_PROTECTcommand.
40h DisablesallwritesexcepttheWRITE_PROTECT,OPERATION,andPAGEcommands.
20h
DisablesallwritesexcepttheWRITE_PROTECT,OPERATION,PAGE,andON_OFF_CONFIG
commands.
00h
Enableswritesforallcommands(default).
PMBus COMMAND RESULTING MEMORY TRANSFER
STORE_DEFAULT_ALL
CopiesRAMOPERATINGtotheashMAIN.
RESTORE_DEFAULT_ALL CopiestheashMAINtoRAMOPERATING.
MFR_STORE_ALL
CODE=00h CopiesRAMOPERATINGtotheashMAIN.
CODE=01h CopiesRAMOPERATINGtotheashBACKUP.
MFR_RESTORE_ALL
CODE=00h CopiestheashMAINarraytoRAMOPERATING.
CODE=01h CopiestheashBACKUPtoRAMOPERATING.
MFR_STORE_SINGLE CopiesRAMOPERATING(singleparameter)totheashSINGLE.
MAIN
CONFIGURATION
CONFIGURATION
FLASH
RAM
BACKUPOPERATING
SINGLE
PMBus
CONTROL AND
MONITORING
ENGINE