HN29W25611T Datasheet, PDF (38/42 Pages) Hitachi Semiconductor – 256M AND type Flash Memory More than 16,057-sector (271,299,072-bit)

HN29W25611T-50H
Requirements for High System Reliability
The device may fail during a program, erase or read operation due to write or erase cycles. The following
architecture will enable high system reliability if a failure occurs.
1. For an error in read operation: An error correction more than 3-bit error correction per each sector read is
required for data reliability.
2. For errors in program or erase operations: The device may fail during a program or erase operation due to
write or erase cycles. The status register indicates if the erase and program operation complete in a finite
time. When an error happens in the sector, try to reprogram the data into another sector. Avoid further
system access to the sector that error happens. Typically, recommended number of a spare sectors are
1.8% of initial usable 16,057 sectors by each device. If the number of failed sectors exceeds the number
of the spare sectors, usable data area in the device decreases. For the reprogramming, do not use the data
from the failed sectors, because the data from the failed sectors are not fixed. So the reprogram data must
be the data reloaded from outer buffer, or use the Data recovery read mode or the Data recovery write
mode (see the “Mode Description” and under figure “Spare Sectors in Program Error”). To avoid
consecutive sector failures, choose addresses of spare sectors as far as possible from the failed sectors.
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