256Mb and 512Mb (256Mb/256Mb), P30-65nm
Security Modes
Security Modes
The device features security modes used to protect the information stored in the flash
memory array. The following sections describe each security mode in detail.
Block Locking
Individual instant block locking is used to protect user code and/or data within the
flash memory array. All blocks power-up in a locked state to protect array data from be-
ing altered during power transitions. Any block can be locked or unlocked with no la-
tency. Locked blocks cannot be programmed or erased; they can only be read.
Software-controlled security is implemented using the Block Lock and Block Unlock
commands. Hardware-controlled security can be implemented using the Block Lock-
Down command along with asserting WP#. Also, V
PP
data security can be used to inhibit
program and erase operations.
Lock Block
To lock a block, issue the Block Lock Setup command, followed by the Block Lock com-
mand issued to the desired block’s address. If the Set Read Configuration Register com-
mand is issued after the Block Lock Setup command, the device configures the RCR in-
stead.
Block lock and unlock operations are not affected by the voltage level on V
PP
. The block
lock bits may be modified and/or read even if V
PP
is at or below V
PPLK
.
Unlock Block
The Block Unlock command is used to unlock blocks. Unlocked blocks can be read,
programmed, and erased. Unlocked blocks return to a locked state when the device is
reset or powered down. If a block is in a lock-down state, WP# must be deasserted be-
fore it can be unlocked.
Lock-Down Block
A locked or unlocked block can be locked-down by writing the Block Lock-Down com-
mand sequence. Blocks in a lock-down state cannot be programmed or erased; they can
only be read. However, unlike locked blocks, their locked state cannot be changed by
software commands alone. A locked-down block can only be unlocked by issuing the
Block Unlock command with WP# deasserted. To return an unlocked block to locked-
down state, a Block Lock-Down command must be issued prior to changing WP# to V
IL
.
Locked-down blocks revert to the locked state upon reset or power up the device.
PDF: 09005aef84566799
p30_65nm_256Mb-512mb.pdf - Rev. A 1/13 EN
40
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