
FLASH MEMORY
13
K9T1G08U0M
Preliminary
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 block
failure rate.The following possible failure modes should be considered to implement a highly reliable system. In the case of status
read failure 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 failure due to single bit error should
be reclaimed by ECC without any block replacement. The block failure rate in the qualification report does not include those
reclaimed blocks.
Program Flow Chart
Start
I/O 6 = 1
or R/B = 1
I/O 0 = 0
No
*
Write 80h
Write Address
Write Data
Write 10h
Read Status Register
Program Completed
Program Error
Yes
No
Yes
Failure Mode
Detection and Countermeasure sequence
Write
Erase Failure
Status Read after Erase --> Block Replacement
Program Failure
Status Read after Program --> Block Replacement
Read
Single Bit Failure
Verify ECC -> ECC Correction
ECC
: Error Correcting Code --> Hamming Code etc.
Example) 1bit correction & 2bits detection
: If program operation results in an error, map out
the block including the page in error and copy the
*
target data to another block.