AT25DF161_13 datasheet(22/52 Pages) ETC2

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AT25DF161

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 first byte of the Status Register will perform a Global Unprotect without changing the state of the

SPRL bit. Similarly, writing a 7Fh to the first byte of the Status Register will perform 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 first byte of 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” to a

Table 9-2.

Valid SPRL and Global Protect/Unprotect Conditions

State

Current

SPRL

Value

New Write Status

Data

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 will remain protected and

all sectors currently unprotected will 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. Therefore, a Global Protect/Unprotect will not occur. In addition,

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 will remain

protected, and all sectors currently unprotected will remain unprotected.

The Sector Protection Registers are soft-locked and cannot be changed when the current

state of SPRL is 1. Therefore, a Global Protect/Unprotect will 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.

3687H–DFLASH–5/2013

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