Rainbow Electronics AT25DF041A - Manual (Page 19)

19
3668E–DFLASH–11/2012
AT25DF041A
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 will perform a Global Unpro-
tect without changing the state of the SPRL bit. Similarly, writing a 7Fh to 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.
Table 9-2. Valid SPRL and Global Protect/Unprotect Conditions
WP
State
Current
SPRL
Value
New
Write Status
Register Data
Protection Operation
New
SPRL
Value Bit
7 6 5 4 3 2 1 0
0 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.
No change to current protection.
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.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
0
0
0
0
0
1
1
1
1
1
0 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).
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.
No change to current protection.
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.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
0
0
0
0
0
1
1
1
1
1
1 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.
0
0
0
0
0
1
1
1
1
1