HY27UF082G2A Datasheet, PDF (40/45 Pages) Hynix Semiconductor – 2Gbit (256Mx8bit/128Mx16bit) NAND Flash

HY27UF(08/16)2G2A Series
2Gbit (256Mx8bit/128Mx16bit) NAND Flash
Bad Block Management
Devices with Bad Blocks have the same quality level and the same AC and DC characteristics as devices where all the blocks are valid.
A Bad Block does not affect the performance of valid blocks because it is isolated from the bit line and common source line by a
select transistor. The devices are supplied with all the locations inside valid blocks erased(FFh).
The Bad Block Information is written prior to shipping. Any block where the 1st Byte / 1st Word in the spare area of the 1st or 2nd
page (if the 1st page is Bad) does not contain FFh is a Bad Block. The Bad Block Information must be read before any erase is
attempted as the Bad Block Information may be erased. For the system to be able to recognize the Bad Blocks based on the original
information it is recommended to create a Bad Block table following the flowchart shown in Figure 26. The 1st block, which is placed
on 00h block address is guaranteed to be a valid block.
Block Replacement
Over the lifetime of the device additional Bad Blocks may develop. 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 will give errors in the Status Regis-
ter.
As 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 the “Copy Back Program” section for more details.
Refer to Table 20 for the recommended procedure to follow if an error occurs during an operation.
Operation
Erase
Program
Read
Recommended Procedure
Block Replacement
Block Replacement or ECC (with 1bit/528byte)
ECC (with 1bit/528byte)
Table 20: Block Failure
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Figure 26: Bad Block Management Flowchart
Rev 0.4 / Mar. 2007
40