FLASH MEMORY

10

K9K2G08U0A

Preliminary

NAND Flash Technical Notes

Identifying Initial Invalid Block(s)

Initial Invalid Block(s)

Initial invalid blocks are defined as blocks that contain one or more initial invalid bits whose reliability is not guaranteed by Samsung.

The information regarding the initial invalid block(s) is so called as the initial invalid block information. Devices with initial invalid

block(s) have the same quality level as devices with all valid blocks and have the same AC and DC characteristics. An initial invalid

block(s) does not affect the performance 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 initial invalid block(s) via address mapping. The 1st block, which is

placed on 00h block address, is fully guaranteed to be a valid block, does not require Error Correction up to 1K Program/Erase

cycles.

All device locations are erased except locations where the initial invalid block(s) information is written prior to shipping. The initial

invalid block(s) status is defined by the 1st byte in the spare area. Samsung makes sure that either the 1st or 2nd page of every initial

invalid block has non-FFh data at the column address of 2048. Since the initial 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 initial

invalid block(s) based on the initial invalid block information and create the initial invalid block table via the following suggested flow

chart(Figure 3). Any intentional erasure of the initial invalid block information is prohibited.

*

Check "FFh" at the column address

Figure 3. Flow chart to create initial invalid block table.

Start

Set Block Address = 0

Check "FFh ?

Increment Block Address

Last Block ?

End

No

Yes

Yes

Create (or update)

No

Initial Invalid Block(s) Table

2048 of the 1st and 2nd page in the block