Linear ANALOG DEVICES LTM4680, Operation Manual

Page: 106 / 126

LTM4680
106
Rev. B
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PMBus COMMAND DETAILS
FAULT WARNING AND STATUS
COMMAND NAME CMD CODE DESCRIPTION TYPE PAGED FORMAT UNITS NVM
DEFAULT
VALUE
CLEAR_FAULTS 0x03 Clear any fault bits that have been set. Send Byte N NA
SMBALERT_MASK 0x1B Mask activity. Block R/W Y Reg Y See CMD
Details
MFR_CLEAR_PEAKS 0xE3 Clears all peak values. Send Byte Y NA
STATUS_BYTE 0x78 One byte summary of the unit’s fault
condition.
R/W Byte Y Reg NA
STATUS_WORD 0x79 Two byte summary of the unit’s fault
condition.
R/W Word Y Reg NA
STATUS_VOUT 0x7A Output voltage fault and warning
status.
R/W Byte Y Reg NA
STATUS_IOUT 0x7B Output current fault and warning
status.
R/W Byte Y Reg NA
STATUS_INPUT 0x7C Input supply fault and warning status. R/W Byte N Reg NA
STATUS_ TEMPERATURE 0x7D External temperature fault and warning
status for READ_TEMERATURE_1.
R/W Byte Y Reg NA
STATUS_CML 0x7E Communication and memory fault and
warning status.
R/W Byte N Reg NA
STATUS_MFR_ SPECIFIC 0x80 Manufacturer specific fault and state
information.
R/W Byte Y Reg NA
MFR_PADS 0xE5 Digital status of the I/O pads. R Word N Reg NA
MFR_COMMON 0xEF Manufacturer status bits that are
common across multiple ADI chips.
R Byte N Reg NA
CLEAR_FAULTS
The CLEAR_FAULTS command is used to clear any fault bits that have been set. This command clears all bits in all
status commands simultaneously. At the same time, the device negates (clears, releases) its ALERT pin signal output
if the device is asserting the ALERT pin signal. If the fault is still present when the bit is cleared, the fault bit will remain
set and the host notified by asserting the ALERT pin low. CLEAR_FAULTS can take up to 10µs to process. If a fault
occurs within that time frame it may be cleared before the status register is set.
This write-only command has no data bytes.
The CLEAR_FAULTS does not cause a unit that has latched off for a fault condition to restart. Units that have shut
down for a fault condition are restarted when:
• 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
• MFR_RESET command is issued.
• Bias power is removed and reapplied to the integrated circuit
SMBALERT_MASK
The SMBALERT_MASK command can be used to prevent a particular status bit or bits from asserting ALERT as they
are asserted.
Figure 52 shows an example of the Write Word format used to set an
ALERT mask, in this case without PEC. The bits in
the mask byte align with bits in the specified status register. For example, if the STATUS_TEMPERATURE command code
is sent in the first data byte, and the mask byte contains 0x40, then a subsequent External Overtemperature Warning