HN29W12811 Datasheet, PDF (38/42 Pages) Hitachi Semiconductor – 128M AND type Flash Memory More than 8,029-sector (135,657,984-bit)

HN29W12811 Series
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 1-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 occurred 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 8,029 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 external buffer, or use the Data recovery read mode or the Data recovery write
mode (see the “Mode Description” and under figure “Spare Sector Replacement Flow after Program
Error”). To avoid consecutive sector failures, choose addresses of spare sectors as far as possible from the
failed sectors.
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