AT45DB021E datasheet(28/69 Pages) RENESAS

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DS-AT45DB021E-8789 Rev. N

Page 28

3/24/26

AT45DB021E Datasheet

10.1.2

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 are 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 are ignored. When

the CS pin is deasserted, the current sector lockdown state is permanently frozen within a time of tLOCK. In

addition, the SLE bit in the Status Register is permanently reset to a Logic 0 to indicate that the Sector Lockdown

command is permanently disabled.

Table 17. Freeze Sector Lockdown

Figure 13. Freeze Sector Lockdown

10.2 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 an 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 Renesas

Electronics and contain a unique value for each device. The factory programmed data is fixed and cannot be

changed.

Table 18. Security Register

Command

Byte 1

Byte 2

Byte 3

Byte 4

Freeze Sector Lockdown

34h

55h

AAh

40h

Security Register Byte Number

· · ·

127

Data Type

One-Time User Programmable

Factory Programmed by Renesas Electronics

34h

55h

AAh

40h

Each transition represents eight bits

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