HY27UG088G5M Datasheet, PDF (44/50 Pages) Hynix Semiconductor – 8Gbit (1Gx8bit) NAND Flash

HY27UG088G(5/D)M Series
8Gbit (1Gx8bit) 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 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 recog-
nize the Bad Blocks based on the original information it is recommended to create a Bad Block table following the flow-
chart shown in Figure 29. The 1st block, which is placed on 00h block address is guaranteed to be a valid block.
Bad 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 Register.
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 18 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/512byte)
ECC (with 1bit/512byte)
Table 18: Block Failure
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Figure 29: Bad Block Management Flowchart
Rev. 0.6 / Dec. 2006
44