at25df041a ATMEL Corporation, at25df041a Datasheet - Page 18

• Manufacturer Part Number: at25df041a
• Description: 4-megabit 2.3-volt Or 2.7-volt Minimum Spi Serial Flash Memory
• Manufacturer: ATMEL Corporation

9.5
Global Protect/Unprotect
The Global Protect and Global Unprotect features can work in conjunction with the Protect Sec-
tor and Unprotect Sector functions. For example, a system can globally protect the entire
memory array and then use the Unprotect Sector command to individually unprotect certain sec-
tors and individually reprotect them later by using the Protect Sector command. Likewise, a
system can globally unprotect the entire memory array and then individually protect certain sec-
tors as needed.
Performing a Global Protect or Global Unprotect is accomplished by writing a certain combina-
tion of data to the Status Register using the Write Status Register command (see “Write Status
Register” section on
page 26
for command execution details). The Write Status Register com-
mand is also used to modify the SPRL (Sector Protection Registers Locked) bit to control
hardware and software locking.
To perform a Global Protect, the appropriate WP pin and SPRL conditions must be met, and the
system must write a logical “1” to bits 5, 4, 3, and 2 of the Status Register. Conversely, to per-
form a Global Unprotect, the same WP and SPRL conditions must be met but the system must
write a logical “0” to bits 5, 4, 3, and 2 of the Status Register.
Table 9-2
details the conditions
necessary for a Global Protect or Global Unprotect to be performed.
AT25DF041A [Preliminary]
18
3668C–DFLASH–3/08