
KAB0xD100M - TxGP
Revision 1.11
August 2003
- 39 -
MCP MEMORY
SEC Only
Error in write operation
Over its life time, the additional invalid blocks may develop with NAND Flash memory. Refer to the qualification report for 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. The said additional block failure
rate does not include those reclaimed blocks.
NOTE:
1. If Program/Erase Cycles is under 1K, Single Bilt Failure do not occure. Therefore there is no need to provide ECC.
2. ECC -> Error Correction Code -> Hamming Code etc.
Example) 1bit error correction and 2 bit error detection
Failure Mode
Detection and Countermeasure sequence
Write
Erase Failure
Status Read after Erase --> Block Replacement
Program Failure
Status Read after Program --> Block Replacement
Read back ( Verify after Program) --> Block Replacement
Read
Single Bit Failure (1)
Verify ECC -> ECC Correction (2)
NAND Flash Technical Notes
Figure 24. Flash Program Flow Chart
Start
I/O 6 = 1
or R/B = 1
Write 00h
I/O 0 = 0
No
*
If ECC is used or program/erase cycles are under 1K,
this verification operation is not needed.
Write 80h
Write Address
Write Data
Write 10h
Read Status Register
Write Address
Wait for tR Time
Verify Data
No
Program Completed
Program Error
Yes
No
Yes
*
Program Error
Yes
: If program operation results in an error, map out
the block including the page in error and copy the
target data to another block.
*