K9W4G08U1M
K9K2G08Q0M
K9K2G08U0M
K9W4G16U1M
K9K2G16Q0M
K9K2G16U0M
FLASH MEMORY
NAND Flash Technical Notes
Invalid Block(s)
Invalid blocks are defined as blocks that contain one or more invalid bits whose reliability is not guaranteed by Samsung. The infor-
mation regarding the invalid block(s) is so called as the invalid block information. Devices with invalid block(s) have the same quality
level as devices with all valid blocks and have the same AC and DC characteristics. An invalid block(s) does not affect the perfor-
mance of valid block(s) because it is isolated from the bit line and the common source line by a select transistor. The system design
must be able to mask out the invalid block(s) via address mapping. The 1st block, which is placed on 00h block address, is guaran-
teed to be a valid block, does not require Error Correction up to 1K program/erase cycles.
Identifying Invalid Block(s)
All device locations are erased(FFh for X8, FFFFh for X16) except locations where the invalid block(s) information is written prior to
shipping. The invalid block(s) status is defined by the 1st byte(X8 device) or 1st word(X16 device) in the spare area. Samsung
makes sure that either the 1st or 2nd page of every invalid block has non-FFh(X8) or non-FFFFh(X16) data at the column address of
2048(X8 device) or 1024(X16 device). Since the invalid block information is also erasable in most cases, it is impossible to recover
the information once it has been erased. Therefore, the system must be able to recognize the invalid block(s) based on the original
invalid block information and create the invalid block table via the following suggested flow chart(Figure 3). Any intentional erasure of
the original invalid block information is prohibited.
Start
Set Block Address = 0
Increment Block Address
Check "FFh( or FFFFh)" at the column address
2048(X8 device) or 1024(X16 device)
of the 1st and 2nd page in the block
*
No
Check "FFh
or FFFFh" ?
Create (or update)
Invalid Block(s) Table
Yes
No
Last Block ?
Yes
End
Figure 3. Flow chart to create invalid block table.
15
SAMSUNG [ SAMSUNG ]
