17
dc2313af
DEMO MANUAL DC2313A
software controL with LtpowerpLay
EEPROM Fault Backup
The LTC2937 stores information about the “first” fault that it
detects into the EEPROM MONITOR_BACKUP register. The
information is a copy of the MONITOR_STATUS_HISTORY
register at the time of the fault. Subsequent power-cycling
has no effect on this stored information, which can be
read with the MONITOR_BACKUP command (0x2F)
after a RESTORE, or a after a power-cycle. This debug
information survives subsequent sequencing operations,
and power cycling. Only the first fault information is stored
in EEPROM. The indicator bit, STATUS_INFORMATION[12]
holds a persistent 1 if the MONITOR_BACKUP register
contains a fault record.
Re-arm the MONITOR_BACKUP register to accept a new
“first” fault by clearing it according to this recipe:
1) Begin in the sequenced-down state. The supplies are
off. The register STATUS_INFORMATION[11:8] = 0x0.
2) Issue a CLEAR command (0x2E) by pressing the “CF”
button in LTpowerPlay. This clears any fault information,
including MONITOR_STATUS_HISTORY.
3) Issue a STORE command (0x2C). This stores the clean
MONITOR_STATUS_HISTORY register contents to
EEPROM. It also stores all configuration registers to
EEPROM.
4) Issue a RESTORE command (0x2D). This restores
the clean MONITOR_BACKUP register contents from
EEPROM. It clears the STATUS_INFORMATION[12]
indicator bit. It also restores all configuration registers
from EEPROM.
Note that it is important to perform the CLEAR and RE-
STORE operations (in that order) while the part is finished
sequencing-down. The internal sequencing state machine
receives a reset when the CLEAR command is issued. If the
LTC2937 is sequenced-up, or in the process of sequenc-
ing, this reset will generate a fault, possibly turn off the
supplies, and re-sequence-up.
Also be aware that the STORE command affects the entire
EEPROM, not only the MONITOR_STATUS_HISTORY
word. This means that any changes that have been made to
the RAM configuration registers will be stored in EEPROM.
Also, if there is newer fault information in RAM than in
the first fault MONITOR_BACKUP register, it will be stored
into EEPROM with a STORE command.
