at25df641 ATMEL Corporation, at25df641 Datasheet - Page 25

• Manufacturer Part Number: at25df641
• Description: At25df641 64-megabit 2.7-volt Minimum Spi Serial Flash Memory
• Manufacturer: ATMEL Corporation

3680B–DFLASH–2/08
Table 9-2.
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-lock-
ing or hardware-locking is desired along with the Global Protect.
State
WP
0
0
1
1
Current
SPRL
Value
0
1
0
1
Valid SPRL and Global Protect/Unprotect Conditions
New Write Status
Register Byte 1
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
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
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
x x x x x x x x
Data
Bit
↕
↕
↕
↕
↕
↕
Protection Operation
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
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).
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
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.
AT25DF641 [Preliminary]
SPRL
Value
New
0
0
0
0
0
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
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