K9F2808U0A Samsung semiconductor, K9F2808U0A Datasheet - Page 9

• Manufacturer Part Number: K9F2808U0A
• Description: 16M x 8 Bit NAND Flash Memory
• Manufacturer: Samsung semiconductor

K9F2808U0A-YCB0, K9F2808U0A-YIB0
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. Typically,
an invalid block will contain a single bad bit. The information regarding the invalid block(s) is so called as the invalid block informa-
tion. Devices with invalid block(s) have the same quality level or as devices with all valid blocks and have the same AC and DC char-
acteristics. An 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 invalid block(s) via address mapping.
The 1st block of the NAND Flash, however, is fully guaranteed to be a valid block.
All device locations are erased(FFh) except locations where the invalid block(s) information is written prior to shipping. The invalid
block(s) status is defined by the 6th byte in the spare area.
block has non-FFh data at the column address of 517. Since the invalid block information is also erasable in most cases, it is impos-
sible 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 1). Any inten-
tional erasure of the original invalid block information is prohibited.
Identifying Invalid Block(s)
Increment Block Address
Invalid Block(s) Table
Create (or update)
Figure 1. Flow chart to create invalid block table.
No
No
Set Block Address = 0
Samsung makes sure that either the 1st or 2nd page of every invalid
Check "FFh" ?
9
Last Block ?
Start
End
Yes
Yes
*
Check "FFh" at the column address 517
of the 1st and 2nd page in the block
FLASH MEMORY