100
Rev. B
For more information
PMBus COMMAND DETAILS
Table 17. IOUT_OC_FAULT_RESPONSE Data Byte Contents
BITS
DESCRIPTION
VALUE MEANING
7:6
Response
For all values of bits [7:6], the LTM4680:
• Sets the corresponding fault bit in the status commands and
• Notifies the host by asserting
ALERT
pin, unless masked.
The fault bit, once set, is cleared only when one or more of the
following events occurs:
• The device receives a CLEAR_FAULTS command.
• The output is commanded through the RUN pin, the OPERATION
command, or the combined action of the RUN pin and
OPERATION command, to turn off and then to turn back on, or
• The device receives a RESTORE_USER_ALL command.
• The device receives a MFR_RESET command.
• The device supply power is cycled.
00
The LTM4680 continues to operate indefinitely while
maintaining the output current at the value set by
IOUT_OC_FAULT_LIMIT without regard to the output
voltage (known as constant-current or brick-wall limiting).
01
Not supported.
10
The LTM4680 continues to operate, maintaining the output
current at the value set by IOUT_OC_FAULT_LIMIT without
regard to the output voltage, for the delay time set by bits [2:0].
If the device is still operating in current limit at the end of the
delay time, the device responds as programmed by the Retry
Setting in bits [5:3].
11
The LTM4680 shuts down immediately and responds as
programmed by the Retry Setting in bits [5:3].
5:3
Retry Setting
000
The unit does not attempt to restart. The output remains
disabled until the fault is cleared by cycling the RUN pin or
removing bias power.
111
The device attempts to restart continuously, without limitation,
until it is commanded OFF (by the RUN pin or OPERATION
command or both), bias power is removed, or another fault
condition causes the unit to shut down. Note: The retry interval
is set by the MFR_RETRY_DELAY command.
2:0
Delay Time
000-111 The number of delay time units in 16ms increments. This
delay time is used to determine the amount of time a unit is
to continue operating after a fault is detected before shutting
down. Only valid for deglitched off response.
Fault Responses IC Temperature
COMMAND NAME
CMD CODE DESCRIPTION
TYPE
PAGED
DATA
FORMAT UNITS
NVM
DEFAULT
VALUE
MFR_OT_FAULT_RESPONSE
0xD6
Action to be taken by the device when an
internal overtemperature fault is detected.
R Byte
N
Reg
0xC0
MFR_OT_FAULT_RESPONSE
The MFR_OT_FAULT_RESPONSE command byte instructs the device on what action to take in response to an internal
overtemperature fault. The data byte is in the format given in Table 18.
The LTM4680 also:
• Sets the NONE_OF_THE_ABOVE bit in the STATUS_BYTE
• Sets the MFR bit in the STATUS_WORD, and
• Sets the Overtemperature Fault bit in the STATUS_MFR_SPECIFIC command
• Notifies the host by asserting
ALERT
pin, unless masked
This command has one data byte.
