K9K1208Q0C
K9K1208D0C
K9K1208U0C
K9K1216Q0C
K9K1216D0C
K9K1216U0C
FLASH MEMORY
NAND Flash Technical Notes (Continued)
Error in write or read operation
Within its life time, the additional invalid blocks may develop with NAND Flash memory. Refer to the qualification report for the actual
data.The following possible failure modes should be considered to implement a highly reliable system. In the case of status read fail-
ure after erase or program, block replacement should be done. Because program status fail during a page program does not affect
the data of the other pages in the same block, block replacement can be executed with a page-sized buffer by finding an erased
empty block and reprogramming the current target data and copying the rest of the replaced block. In case of Read, ECC must be
employed. To improve the efficiency of memory space, it is recommended that the read or verification failure due to single bit error be
reclaimed by ECC without any block replacement. The said additional block failure rate does not include those reclaimed blocks.
Failure Mode
Erase Failure
Detection and Countermeasure sequence
Status Read after Erase --> Block Replacement
Status Read after Program --> Block Replacement
Verify ECC -> ECC Correction
Write
Read
Program Failure
Single Bit Failure
: Error Correcting Code --> Hamming Code etc.
Example) 1bit correction & 2bit detection
ECC
Program Flow Chart
Start
Write 80h
Write Address
Write Data
Write 10h
Read Status Register
No
I/O 6 = 1 ?
or R/B = 1 ?
Yes
*
No
Program Error
I/O 0 = 0 ?
Yes
Program Completed
: If program operation results in an error, map out
the block including the page in error and copy the
target data to another block.
*
15
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