EN27LN4G08 Datasheet, PDF (12/54 Pages) Eon Silicon Solution Inc. – 4 Gigabit (512M x 8), 3.3 V NAND Flash Memory

EN27LN4G08
NAND Flash Technical Notes
Mask Out 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 Eon. The information regarding the initial invalid block(s) is called 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 guaranteed to be a valid block up to 1K
program/erase cycles with 4 bit/512 bytes ECC.
Identifying Initial Invalid Block(s) and Block Replacement Management
Unpredictable behavior may result from programming or erasing the defective blocks. Figure on next
page illustrates an algorithm for searching factory-mapped defects, and the algorithm needs to be
executed prior to any erase or program operations.
A host controller has to scan blocks from block 0 to the last block using page read command and check
the data at the 1st byte column address in the spare area of the 1st and 2nd page in the block. If the
read data is not FFh, the block is interpreted as an invalid block. The initial invalid block information is
erasable, and which is impossible to be recovered once it has been erased. Therefore, the host
controller must be able to recognize the initial invalid block information and to create a corresponding
table to manage block replacement upon erase or program error when additional invalid blocks develop
with Flash memory usage.
This Data Sheet may be revised by subsequent versions
12
or modifications due to changes in technical specifications.
©2013 Eon Silicon Solution, Inc., www.eonssi.com
Rev. A, Issue Date: 2013/10/03