Datasheet

LTC2974
70
2974fc
For more information www.linear.com/LTC2974
pMbus coMManD DescripTion
Fault Log Operation
A conceptual diagram of the fault log is shown in Figure 22. The fault log provides black box capability for the LTC2974.
During normal operation the contents of the status registers, the output voltage/current/temperature readings, the
input voltage readings, as well as peak and min values of these quantities, are stored in a continuously updated buffer
in RAM. You can think of the operation as being similar to a strip chart recorder. When a fault occurs, the contents are
written into EEPROM for non volatile storage. The EEPROM fault log is then locked. The part can be powered down
with the fault log available for reading at a later time.
Figure 22: Fault Logging
2974 F22
ADC READINGS
CONTINUOUSLY
FILL BUFFER
TIME OF FAULT
TRANSFER TO
EEPROM AND
LOCK
AFTER FAULT
READ FROM
EEPROM AND
LOCK BUFFER
RAM 255 BYTES EEPROM 255 BYTES
8
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.
.
.
.
.
MFR_FAULT_LOG_STORE
This command allows the user to transfer data from the RAM buffer to EEPROM.
MFR_FAULT_LOG_RESTORE
This command allows the user to transfer a copy of the fault-log data from the EEPROM to the RAM buffer. After a
restore the RAM buffer is locked until a successful MFR_FAULT_LOG read.
FAULT LOGGING
COMMAND NAME
CMD
CODE DESCRIPTION TYPE PAGED FORMAT UNITS EEPROM
DEFAULT
VALUE
REF
PAGE
MFR_FAULT_LOG_STORE 0xEA Command a transfer of the fault log from
RAM to EEPROM.
Send Byte N NA
70
MFR_FAULT_LOG_RESTORE 0xEB Command a transfer of the fault log
previously stored in EEPROM back to RAM.
Send Byte N NA
70
MFR_FAULT_LOG_CLEAR 0xEC Initialize the EEPROM block reserved for
fault logging and clear any previous fault
logging locks.
Send Byte N NA
71
MFR_FAULT_LOG_STATUS 0xED Fault logging status. R Byte N Reg Y NA
71
MFR_FAULT_LOG 0xEE Fault log data bytes. This sequentially
retrieved data is used to assemble a
complete fault log.
R Block N Reg Y NA
71