Datasheet

MAX34451 PMBus 16-Channel V/I Monitor and
12-Channel Sequencer/Marginer
www.maximintegrated.com
Maxim Integrated │ 19
Host Sends or Reads Too Few Bits
If, for any reason, the host does not complete writing a full
byteorreadingafullbytefromthedevicebeforeaSTART
orSTOPisreceived,thedevicedoesthefollowing:
1) Ignoresthecommand.
2) SetstheCMLbitinSTATUS_WORD.
3) SetstheDATA_FAULTbitinSTATUS_CML.
4) NotifiesthehostthroughALERTassertion(ifenabled).
Host Sends or Reads Too Few Bytes
Foreachsupportedcommand,thedeviceexpectsafixed
number of bytes to be written to or read from the device.
If, for any reason, less than the expected number of bytes
are written to or read from the device, the device com-
pletely ignores the command and takes no action.
Host Sends Too Many Bytes or Bits
Foreachsupportedcommand,thedeviceexpectsafixed
number of bytes to be written to the device. If for any
reason, more than the expected number of bytes or bits is
writtentothedevice,thedevicedoesthefollowing:
1) Ignoresthecommand.
2) SetstheCMLbitinSTATUS_WORD.
3) SetstheDATA_FAULTbitinSTATUS_CML.
4) NotifiesthehostthroughALERTassertion(ifenabled).
Host Reads Too Many Bytes or Bits
Foreachsupportedcommand,thedeviceexpectsafixed
number of bytes to be read from the device. If, for any
reason, more than the expected number of bytes or bits is
readfromthedevice,thedevicedoesthefollowing:
1) Sends all ones (FFh) as long as the host keeps
acknowledging.
2) SetstheCMLbitinSTATUS_WORD.
3) SetstheDATA_FAULTbitinSTATUS_CML.
4) NotifiesthehostthroughALERTassertion(ifenabled).
Host Sends Improperly Set Read Bit in the
Slave Address Byte
IfthedevicereceivestheR/W bit in the slave address set
to a one immediately preceding the command code, the
devicedoesthefollowing(thisdoesnotapplytotheARA):
1) ACKstheaddressbyte.
2) Sends all ones (FFh) as long as the host keeps
acknowledging.
3) SetstheCMLbitinSTATUS_WORD.
4) SetstheDATA_FAULTbitinSTATUS_CML.
5) NotifiesthehostthroughALERTassertion(ifenabled).
Unsupported Command Code Received/Host
Writes to a Read-Only Command
If the host sends the device a command code that it does
not support, or if the host sends a command code that
isnotsupportedbythecurrentPAGEsetting,thedevice
doesthefollowing:
1) Ignoresthecommand.
2) SetstheCMLbitinSTATUS_WORD.
3) SetstheCOMM_FAULTbitinSTATUS_CML.
4) NotifiesthehostthroughALERTassertion(ifenabled).
Invalid Data Received
ThedevicechecksthePAGE,OPERATION,andWRITE_
PROTECT command codes for valid data. If the host
writes a data value that is invalid, the device does the
following:
1) Ignoresthecommand.
2) SetstheCMLbitinSTATUS_WORD.
3) SetstheDATA_FAULTbitinSTATUS_CML.
4) NotifiesthehostthroughALERTassertion(ifenabled).
Host Reads from a Write-Only Command
When a read request is issued to a write-only
command (CLEAR_FAULTS, STORE_DEFAULT_
ALL, RESTORE_DEFAULT_ALL, MFR_STORE_ALL,
MFR_RESTORE_ALL,OPERATIONwithPAGE=255),
thedevicedoesthefollowing:
1) ACKstheaddressbyte.
2) Ignoresthecommand.
3) Sends all ones (FFh) as long as the host keeps
acknowledging.
4) SetstheCMLbitinSTATUS_WORD.
5) SetstheDATA_FAULTbitinSTATUS_CML.
6) NotifiesthehostthroughALERTassertion(ifenabled).
SMBus Timeout
If, during an active SMBus communication sequence,
the SCLsignal is heldlow for greaterthan the timeout
duration (nominally 27ms), the device terminates the
sequence and resets the serial bus. It takes no other
action.Nostatusbitsareset.