K9F3208W0A-TCB0, K9F3208W0A-TIB0

FLASH MEMORY

10

NAND Flash Technical Notes (Continued)

Program Flow Chart

Start

I/O 6 = 1 ?

Write 00h

I/O 0 = 0 ?

No

*

If ECC is used, this verification

Write 80h

Write Address

Write Data

Write 10h

Read Status Register

Write Address

Wait for tR Time

Verify Data

No

Program Completed

or R/B = 1 ?

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.

*

operation is not needed.

Error in write or read operation

Over 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. To improve the efficiency of mem-

ory 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

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

or ECC Correction

Read

Single Bit Failure

Verify ECC -> ECC Correction

ECC

: Error Correcting Code --> Hamming Code etc.

Example) 1bit correction & 2bit detection