DS2731
Cache-Memory Battery-Backup Management IC
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Reapplication of Power
This is essentially the reverse process from the power-
loss sequence. Power is applied to the RAID card; the
12V and 3.3V buses turn on and become stable. The
main cache-memory power supply turns on but the
power MOSFET that connects the cache to the cache-
power supply remains off. The cache-backup supply in
the DS2731 automatically switches from the battery
source to the 3.3V bus when the 3.3V bus goes above
2.93V. The system then disables ENS and enables the
cache’s power MOSFET, connecting the cache to the
main cache power supply. Enough bulk storage capac-
itance must be available at the cache to hold up during
this switchover time. The memory is now ready to exit
from autorefresh mode (IDD6 for DDR2 memory) and
resume full operation.
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages
.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
28 TSSOP —
21-0108
