H27UAG8T2B Datasheet, PDF (12/61 Pages) Hynix Semiconductor – 16Gb (2048M x 8bit) NAND Flash

Release
H27UAG8T2B Series
16Gb (2048M x 8bit) NAND Flash
1.9. 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 either
the 1st or the last page 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 Flow chart
1(Bad block management flow chart). The 1st block, which is placed on 00h block address, is guaranteed to be a valid
block at the time of shipment.
■ Flow chart 1. Bad block management flow chart
Start
Block No = 0
Read FFh
check column 8192
of the first page
Block No. = Block No. + 1
Pass
Read FFh
check col. 8192
of the last page
Pass
Fail
Fail
Entry Bad Block
No
Last Block
Yes
End
Notes:
1. Do not try to erase the detected bad blocks, because the bad block information will be lost.
2. Do not perform program and erase operation in invalid block, it is impossible to guarantee the input data
and to ensure that the function is normal.
Rev 1.0 / Aug. 2010
12