AT25SL321 datasheet(68/82 Pages) DIALOG

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AT25SL321

DS-25SL321–112H–2020-10

8.40 Write Security Register (2Fh)

The Write Security Register instruction is for changing the values of Security Register bits. Unlike the Write Status

The Write Security Register instruction can change the value of bit1 (LDSO bit) for customer to lock-down the 4

kbit Secured OTP area. Once the LDSO bit is set to “1”, the Secured OTP area cannot be updated any more.

The CS must go high exactly at the boundary; otherwise, the instruction are rejected and not executed.

Figure 8-63. Write Security Register Instruction for SPI Mode (left) and QPI Mode (right)

8.41 4 kbit Secured OTP

It’s for unique identifier to provide 4 kbit one-time-program area for setting device unique serial number which

can be set by factory or system customer. See Table 8-13, Secured OTP Address Space.

•

Security register bit 0 indicates whether the chip is locked by the factory or not.

•

To program the 4 kbit secured OTP by entering 4 kbit secured OTP mode (with ENSO command) and going

through normal program procedure, and then exiting 4 kbit secured OTP mode by writing the EXSO

command.

•

Customer might lock-down bit 1 as ‘1’. See Table 8-13, Secured OTP Address Space.

Note. Once lock-down whatever by factory or customer, it cannot be changed any more. While in 4 kbit secured

OTP mode, write access to the array is not allowed.

Table 8-13. Secured OTP Address Space

Address Range

Size

Standard

Customer Lock

000000 ~ 00000F

128-bit

ESN

(Electrical Serial Number)

Determined by customer

000010 ~ 0001FF

3968-bit

N/A

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