MT29F8G08FACWP Micron Technology, MT29F8G08FACWP Datasheet - Page 40

• Manufacturer Part Number: MT29F8G08FACWP
• Description: NAND Flash Memory
• Manufacturer: Micron Technology

Figure 35:
Error Management
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2_4_8gb_nand_m49a__2.fm - Rev. A 3/06 EN
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PROGRAM Disable
Micron NAND Flash devices are specified to have a minimum of 2,008 (N
out of every 2,048 total available blocks. This means the devices may have blocks that are
invalid when they are shipped. An invalid block is one that contains one or more bad
bits. Additional bad blocks may develop with use. However, the total number of avail-
able blocks will not fall below N
Although NAND Flash memory devices may contain bad blocks, they can be used quite
reliably in systems that provide bad-block mapping, bad-block replacement, and error
correction algorithms. This type of software environment ensures data integrity.
Internal circuitry isolates each block from other blocks, so the presence of a bad block
does not affect the operation of the rest of the Flash device.
The first block (physical block address 00h) for each CE#is guaranteed to be free of
defects (up to 1,000 PROGRAM/ERASE cycles) when shipped from the factory. This pro-
vides a reliable location for storing boot code and critical boot information.
Before NAND Flash devices are shipped from Micron, they are erased. The factory iden-
tifies invalid blocks before shipping by programming data other than FFh (x8) or FFFFh
(x16) into the first spare location (column address 2,048 for x8 devices, or column
address 1,024 for x16 devices) of the first or second page of each bad block.
System software should check the first spare address on the first two pages of each block
prior to performing any erase or programming operations on the NAND Flash device. A
bad block table can then be created, allowing system software to map around these
areas. Factory testing is performed under worst-case conditions. Because blocks marked
“bad” may be marginal, it may not be possible to recover this information if the block is
erased.
Over time, some memory locations may fail to program or erase properly. In order to
ensure that data is stored properly over the life of the NAND Flash device, certain pre-
cautions must be taken, such as:
• Always check status after a PROGRAM, ERASE, or DATA MOVE operation.
• Use some type of error detection and correction algorithm to recover from single-bit
• Use a bad-block replacement algorithm.
WE#
WP#
R/B#
I/Ox
errors per 528 bytes of data.
t WW
80h
40
2Gb, 4GB, 8Gb: x8, x16 NAND Flash Memory
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during the endurance life of the product.
10h
Micron Technology, Inc., reserves the right to change products or specifications without notice.
©2005 Micron Technology, Inc. All rights reserved.
Error Management
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) valid blocks