Samsung MUXONENAND A-DIE KFM2G16Q2A - Manual (Page 135)

MuxOneNAND2G(KFM2G16Q2A-DEBx)
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FLASH MEMORY
MuxOneNAND4G(KFN4G16Q2A-DEBx)
3.17 ECC Operation
The MuxOneNAND device has on-chip ECC with the capability of detecting 2 bit errors and correcting 1-bit errors in the NAND Flash Array
memory main and spare areas.
As the device transfers data from a BufferRAM to the NAND Flash Array memory Page Buffer for Program Operation, the device initiates a
background operation which generates an Error Correction Code (ECC) of 24bits for each sector main area data and 10bits for 2nd and 3rd
word data of each sector spare area.
During a Load operation from the NAND Flash Array memory Page, the on-chip ECC engine generates a new ECC. The 'Load ECC result' is
compared to the originally 'Program ECC' thus detecting the number and position of errors. Single-bit error is corrected.
ECC is updated by the device automatically. After a Load Operation, the Host can determine whether there was error by reading the 'ECC Sta-
tus Register' (refer to section 2.8.26).
Error types are divided into 'no error', '1bit correctable error', and '2bit error uncorrectable error'.
MuxOneNAND supports 2bit EDC even though 2bit error seldom or never occurs. Hence, it is not recommended for Host to read 'ECC Status
Register' for checking ECC error because the built-in Error Correction Logic of MuxOneNAND automatically corrects ECC error.
When the device reads the NAND Flash Array memory main and spare area data with an ECC operation, the device doesn't place the newly
generated ECC for main and spare area into the buffer. Instead it places the ECC which was generated and written during the program oper-
ation into the buffer.
An ECC operation is also done during the Boot Loading operation.
3.17.1 ECC Bypass Operation
n an ECC bypass operation, the device does not generate ECC as a background operation. The result does not indicate error position (refer
to the ECC Result Table).
In a Program Operation the ECC code to NAND Flash Array memory spare area is not updated.
During a Load operation, the on-chip ECC engine does not generate a new ECC internally. Also the ECC Status & Result to Registers are
invalid. The error is not corrected and detected by itself, so that ECC bypass operation is not recommended for host.
ECC bypass operation is set by the 9bit of System Configuration 1 Register (see section 2.8.19).
In case of ECC Bypass, user can program in ECC Area.
ECC Code and ECC Result by ECC Operation
NOTE :
1) Pre-written ECC code : ECC code which is previously written to NAND Flash Spare Area in program operation.
Operation
Program operation Load operation
ECC Code Update to NAND
Flash Array Spare Area
ECC Code at BufferRAM Spare
Area
ECC Status & Result Update
to Registers
1bit Error
ECC operation Update Pre-written ECC code (1) loaded Update Correct
ECC bypass Not update Pre-written code (1) loaded Invalid Not correct