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PMBus COMMAND DETAILS
TOFF_MAX_WARN_LIMIT
The TOFF_MAX_WARN_LIMIT command sets the value, in milliseconds, on how long the output voltage exceeds
12.5% of the programmed voltage before a warning is asserted. The output is considered off when the V
is less than 12.5% of the programmed VOUT_COMMAND value. The calculation begins after TOFF_FALL is complete.
A data value of 0ms means there is no limit, and the output voltage exceeds 12.5% of the programmed voltage indefi-
nitely. Other than 0, values from 120ms to 524 seconds are valid.
This command has two data bytes and is formatted in Linear_5s_11s format.
Precondition for Restart
COMMAND NAME
CMD CODE DESCRIPTION
MFR_RESTART_DELAY
0xDC
MFR_RESTART_DELAY
This command specifies the minimum RUN off time in milliseconds. This device will pull the RUN pin low for this length
of time once a falling edge of RUN has been detected. The minimum recommended value is 136ms.
NOTE: The restart delay is different from the retry delay. The restart delay pulls RUN low for the specified time,
after which a standard start-up sequence is initiated. The minimum restart delay should be equal to TOFF_DELAY +
TOFF_FALL + 136ms. Valid values are from 136ms to 65.52 seconds in 16ms increments. To ensure a minimum off
time, set the MFR_RESTART_DELAY 16ms longer than the desired time. The output rail can be off longer than the
MFR_RESTART_DELAY after the RUN pin is pulled high if the output decay bit 0 is enabled in MFR_CHAN_CONFIG
and the output takes a long time to decay below 12.5% of the programmed value.
This command has two data bytes and is formatted in Linear_5s_11s format.
FAULT RESPONSE
Fault Responses All Faults
COMMAND NAME
CMD CODE DESCRIPTION
MFR_RETRY_DELAY
MFR_RETRY_DELAY
This command sets the time in milliseconds between retries if the fault response is to retry the controller at specified
intervals. This command value is used for all fault responses that require retry. The retry time starts once the fault has
been detected by the offending channel. Valid values are from 120ms to 83.88 seconds in 10µs increments.
NOTE: The retry delay time is determined by the length of the MFR_RETRY_DELAY command or the time required
for the regulated output to decay below 12.5% of the programmed value. If the natural decay time of the output is
too long, it is possible to remove the voltage requirement of the MFR_RETRY_DELAY command by asserting bit 0 of
MFR_CHAN_CONFIG.
This command has two data bytes and is formatted in Linear_5s_11s format.
Minimum time the RUN pin is held
low by the LTM4683.
0xDB
Retry interval during FAULT
retry mode.
For more information
DATA
TYPE
PAGED
FORMAT
R/W Word
Y
L11
DATA
TYPE
PAGED
FORMAT
R/W Word
Y
L11
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LTM4683
voltage
OUT
DEFAULT
UNITS
NVM
VALUE
ms
Y
150
0xF258
DEFAULT
UNITS
NVM
VALUE
ms
Y
250
0xF3E8
Rev. 0
101
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