TH58NVG5S0FTA20 Datasheet, PDF (68/73 Pages) Toshiba Semiconductor – 32 GBIT (4G × 8 BIT) CMOS NAND E2PROM

TOSHIBA CONFIDENTIAL TH58NVG5S0FTA20
(13) Invalid blocks (bad blocks)
The device occasionally contains unusable blocks. Therefore, the following issues must be recognized:
Bad Block
Bad Block
Please do not perform an erase operation to bad blocks. It may be
impossible to recover the bad block information if the information is
erased.
Check if the device has any bad blocks after installation into the system.
Refer to the test flow for bad block detection. Bad blocks which are
detected by the test flow must be managed as unusable blocks by the
system.
A bad block does not affect the performance of good blocks because it is
isolated from the bit lines by select gates.
The number of valid blocks over the device lifetime is as follows:
MIN
TYP.
MAX
UNIT
Valid (Good) Block Number 16064
⎯
16384
Block
Bad Block Test Flow

Regarding invalid blocks, bad block mark is in either the 1st or the 2nd page.
Start
Read Check :
Read either column 0 or 4096 of the 1st page or the
2nd page of each block. If the data of the column is not
FF (Hex), define the block as a bad block.
Block No = 1
Block No. = Block No. + 1
Read Check
Pass
Fail
Bad Block *1
No
Last Block
Yes
End
*1:
No erase operation is allowed to detected bad blocks
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2010-12-13C