256Mb and 512Mb (256Mb/256Mb), P30-65nm
Security Operations
Security Operations
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 UN-
LOCK commands. Hardware-controlled security can be implemented using the BLOCK
LOCK DOWN command along with asserting WP#. Also, VPP data security can be used
to inhibit PROGRAM and ERASE operations.
BLOCK LOCK Command
To lock a block, issue the BLOCK LOCK SETUP command, followed by the BLOCK LOCK
command issued to the desired block’s address. If the SET READ CONFIGURATION
REGISTER command is issued after the BLOCK LOCK SETUP command, the device
configures the RCR instead.
BLOCK LOCK and UNLOCK operations are not affected by the voltage level on VPP. The
block lock bits may be modified and/or read even if VPP is at or below VPPLK
.
BLOCK UNLOCK Command
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 de-asserted be-
fore it can be unlocked.
BLOCK LOCK DOWN Command
A locked or unlocked block can be locked-down by writing the BLOCK LOCK DOWN
command 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# de-asserted. To return an unlocked
block to locked-down state, a BLOCK LOCK DOWN command must be issued prior to
changing WP# to VIL. Locked-down blocks revert to the locked state upon reset or power
up the device.
Block Lock Status
The READ DEVICE IDENTIFIER command is used to determine a block’s lock status.
DQ[1:0] display the addressed block’s lock status; DQ0 is the addressed block’s lock bit,
while DQ1 is the addressed block’s lock-down bit.
PDF: 09005aef84566799
p30_65nm_MLC_256Mb-512mb.pdf - Rev. C 12/13 EN
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