AT25DF021A-DWFHT datasheet(26/59 Pages) RENESAS

26 / 59 page

DS-AT25DF021A-042 Rev. L

Page 26

8/7/23

AT25DF021A Datasheet

Essentially, if the SPRL bit of the Status Register is in the logical 0 state (Sector Protection Registers are not

locked), then writing a 00h to the Status Register performs a Global Unprotect without changing the state of the

SPRL bit. Similarly, writing a 7Fh to the Status Register performs a Global Protect and keep the SPRL bit in the

logical 0 state. The SPRL bit can, of course, be changed to a logical 1 by writing an FFh if software-locking or

hardware-locking is desired along with the Global Protect.

If the desire is to only change the SPRL bit without performing a Global Protect or Global Unprotect, then the

system can simply write a 0Fh to the Status Register to change the SPRL bit from a logical 1 to a logical 0

provided the WP pin is deasserted. Likewise, the system can write an F0h to change the SPRL bit from a logical 0

Table 4. Valid SPRL and Global Protect/Unprotect Conditions

State

Current

SPRL

Value

New

Write Status

Protection Operation

New

SPRL

Value

Bit

7 6 5 4 3 2 1 0

0 x 0 0 0 0 x x

0 x 0 0 0 1 x x

0 x 1 1 1 0 x x

0 x 1 1 1 1 x x

1 x 0 0 0 0 x x

1 x 0 0 0 1 x x

1 x 1 1 1 0 x x

1 x 1 1 1 1 x x

Global Unprotect – all Sector Protection Registers reset to 0

No change to current protection.

Global Protect – all Sector Protection Registers set to 1

Global Unprotect – all Sector Protection Registers reset to 0

No change to current protection.

Global Protect – all Sector Protection Registers set to 1

x x x x x x x x

No change to the current protection level. All sectors currently protected remain

protected and all sectors currently unprotected remain unprotected.

The Sector Protection Registers are hard-locked and cannot be changed when

the WP pin is LOW and the current state of SPRL is 1. Thus, a Global

Protect/Unprotect does not occur. Also, the SPRL bit cannot be changed (the

WP pin must be HIGH in order to change SPRL back to a 0).

0 x 0 0 0 0 x x

0 x 0 0 0 1 x x

0 x 1 1 1 0 x x

0 x 1 1 1 1 x x

1 x 0 0 0 0 x x

1 x 0 0 0 1 x x

1 x 1 1 1 0 x x

1 x 1 1 1 1 x x

Global Unprotect – all Sector Protection Registers reset to 0

No change to current protection.

Global Protect – all Sector Protection Registers set to 1

Global Unprotect – all Sector Protection Registers reset to 0

No change to current protection.

Global Protect – all Sector Protection Registers set to 1

0 x 0 0 0 0 x x

0 x 0 0 0 1 x x

0 x 1 1 1 0 x x

0 x 1 1 1 1 x x

1 x 0 0 0 0 x x

1 x 0 0 0 1 x x

1 x 1 1 1 0 x x

1 x 1 1 1 1 x x

No change to the current protection level. All sectors currently

protected remain protected, and all sectors currently unprotected

remain unprotected.

The Sector Protection Registers are soft-locked and cannot be

changed when the current state of SPRL is 1. Thus, a Global

Protect/Unprotect does not occur. However, the SPRL bit can be

changed back to a 0 from a 1 since the WP pin is HIGH. To perform

a Global Protect/Unprotect, the Write Status Register command

must be issued again after the SPRL bit has been changed from a 1

to a 0.

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