OneNAND512/OneNAND1GDDP
FLASH MEMORY
64
Technical Notes
Identifying Invalid Block(s)
All device locations are erased(FFFFh) except locations where the invalid block(s) information is written prior to shipping. The invalid
block(s) status is defined by the 1st word in the spare area. Samsung makes sure that either the 1st or 2nd page of every invalid
block has non-FFFFh data at the 1st word of sector0 spare area. 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. Any
intentional erasure of the original invalid block information is prohibited.
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 fully guar-
anteed to be a valid block.
*
Figure 22. Flow chart to create invalid block table.
Start
Set Block Address = 0
Check "
FFFFh"
Increment Block Address
Last Block
End
No
Yes
Yes
Create (or update)
Invalid Block(s) Table
No
Check "FFFFh" at the 1st word
of sector0 spare area at the 1st
and 2nd page in the block