NAND08GW3C2A Datasheet, PDF (34/58 Pages) Numonyx B.V – 8/16 Gbit, 2112 byte page, 3 V supply, multilevel, multiplane, NAND Flash memory

Software algorithms
NAND08GW3C2A, NAND16GW3C2A
9.2
NAND Flash memory failure modes
The NAND08GW3C2A and NAND16GW3C2A devices may contain bad blocks, where the
reliability of blocks that contain one or more invalid bits is not guaranteed. Additional bad
blocks may develop during the lifetime of the device.
To implement a highly reliable system, all the possible failure modes must be considered:
● Program/erase failure
in this case, the block has to be replaced by copying the data to a valid block. These
additional bad blocks can be identified as attempts to program or erase them and will
give errors in the Status Register.
Because the failure of a Page Program operation does not affect the data in other
pages in the same block, the block can be replaced by re-programming the current data
and copying the rest of the replaced block to an available valid block. The Copy Back
Program command can be used to copy the data to a valid block. See Section Figure
10.: Random Data Input during Sequential Data Input for more details.
● Read failure
in this case, ECC correction must be implemented. To efficiently use the memory
space, it is recommended to recover single-bit errors in read by ECC, without replacing
the whole block.
Refer to Table 14 for the procedure to follow if an error occurs during an operation.
Table 14.
Block failure
Operation
Erase
Program
Read
Procedure
Block replacement
Block replacement or ECC (with 4 bit/528 byte)
ECC (with 4 bit/528 byte)
34/58