Samsung KFN8GH6Q4M, KFKAGH6Q4M 13.4 1st Block OTP Lock Operation, Locking the 1st Block OTP

Flex-MuxOneNAND4G(KFM4GH6Q4M-DEBx)
Flex-MuxOneNAND8G(KFN8GH6Q4M-DEBx)
Flex-MuxOneNAND16G(KFKAGH6Q4M-DEBx)	FLASH MEMORY

3.13.4 1st Block OTP Lock Operation

1st Block can be used as OTP, for secured booting operation.

1st Block OTP can be accessed just as any other NAND Flash Array Blocks before it is locked, however, once 1st Block is locked to be OTP, 1st Block OTP cannot be erased or programmed.

Note that once OTP Block is locked, 1st Block OTP lock is impossible also OTP Block cannot be locked freely after locking 1st Block OTP. OTP Block and 1st Block OTP should be locked at the same time.

Locking the 1st Block OTP

Programming to the 1st Block OTP area can be prevented by locking the OTP area. Locking the OTP area is accomplished by programming XXF3h to the 1st word of sector4 of main of the page49 memory area in the OTP block.

At device power-up, this word location is checked and if XXF3h is found, the OTPBL bit of the Controller Status Register is set to "1", indicating

the 1st Block is locked. When the Program Operation finds that the status of the 1st Block is locked, the device updates the Error Bit of the Controller Status Register as "1" (fail).

1st Block OTP Lock Operation Steps

•Issue the OTP Access Command

•Fill data to be programmed into DataRAM (data can be input at anytime between the "Start" and "Write Program" commands)

•Write ‘XXF3h’ data into the 1st word of sector4 of main of the page49 memory area of the DataRAM.

•Issue a Flash Block Address (FBA) which is 0000h of NAND Flash Array address map.

•Issue a Program command to program the data from the DataRAM into the OTP

•When the 1st Block OTP lock is complete, do a Cold Reset to exit the OTP Access mode and update 1st Block OTP lock bit[5].

•1st Block OTP lock bit[5] of the Controller Status Register will be set to "1" and the 1st Block will be locked.

Even though the OTP area can only be programmed once without erase capability, it can be locked when the device starts up to prevent any changes from being made.

Unlike other remaining main area of the NAND Flash Array memory, once the 1st block OTP is locked, it cannot be unlocked.

Once 1st block is set as OTP, NAND Flash Write Protection status register(F24Eh) indicates only ‘Lock’ state although ‘Lock tight’ or ‘Unlock’ command is issued.

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