AT45DB321E datasheet(24/69 Pages) RENESAS

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AT45DB321E

8784M–DFLASH–02/2022

Figure 7-2.

Read Sector Lockdown Register

7.1.2

Freeze Sector Lockdown

The Sector Lockdown command can be permanently disabled, and the current sector lockdown state can be

permanently frozen so that no additional sectors can be locked down aside from those already locked down. Any

attempts to issue the Sector Lockdown command after the Sector Lockdown State has been frozen will be ignored.

To issue the Freeze Sector Lockdown command, the CS pin must be asserted and the opcode sequence of 34h, 55h,

AAh, and 40h must be clocked into the device. Any additional data clocked into the device will be ignored. When the CS

pin is deasserted, the current sector lockdown state will be permanently frozen within a time of t

LOCK. In addition, the SLE

bit in the Status Register will be permanently reset to a Logic 0 to indicate that the Sector Lockdown command is

permanently disabled.

Table 7-5.

Freeze Sector Lockdown

Figure 7-3.

Freeze Sector Lockdown

7.2

Security Register

The device contains a specialized Security Register that can be used for purposes such as unique device serialization or

locked key storage. The register is comprised of a total of 128 bytes that is divided into two portions. The first 64 bytes

(byte locations 0 through 63) of the Security Register are allocated as a One-Time Programmable space. Once these 64

bytes have been programmed, they cannot be erased or reprogrammed. The remaining 64 bytes of the register (byte

locations 64 through 127) are factory programmed by Adesto and will contain a unique value for each device. The factory

programmed data is fixed and cannot be changed.

Table 7-6.

Security Register

35h

Data

n + 1

Data

n + 63

Each transition represents eight bits

Command

Byte 1

Byte 2

Byte 3

Byte 4

Freeze Sector Lockdown

34h

55h

AAh

40h

34h

55h

AAh

40h

Each transition represents eight bits

Security Register Byte Number

· · ·

127

Data Type

One-Time User Programmable

Factory Programmed by Adesto

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