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3.2.3
Unlocked State
Unlocked blocks (states [000], [100], [110]) can be programmed or erased. All unlocked blocks
return to the locked state when the device is reset or powered down. The status of an unlocked
block can be changed to locked or locked-down using the appropriate command. A locked block
can be unlocked by writing the Unlock command sequence, 60H followed by D0H.
3.2.4
Lock-Down State
Blocks that are locked-down (state [011]) are protected from program and erase operations (just
like locked blocks), but their protection status cannot be changed using software commands alone.
A locked or unlocked block can be locked-down by writing the Lock-Down command sequence,
60H followed by 2FH. Locked-down blocks revert to the locked state when the device is reset or
powered down.
The Lock-Down function is dependent on the WP# input pin. When WP# = 0, blocks in lock-down
[011] are protected from program, erase, and lock status changes. When WP# = 1, the lock-down
function is disabled ([111]) and locked-down blocks can be individually unlocked by software
command to the [110] state, where they can be erased and programmed. These blocks can then be
re-locked [111] and unlocked [110] as desired while WP# remains high. When WP# goes low,
blocks that were previously locked-down return to the lock-down state [011] regardless of any
changes made while WP# was high. Device reset or power-down resets all blocks, including those
in lock-down, to locked state.
3.2.5
Reading a Block’s Lock Status
The lock status of every block can be read in the device identifier read mode of the device. To enter
this mode, write 90H to the device. Subsequent reads at Block Base Address + 00002 will output
the lock status of that block. The lock status is represented by the lowest two output pins, DQ
0
and
DQ
1
. DQ
0
indicates the block lock/unlock status and is set by the Lock command and cleared by
the Unlock command. It is also automatically set when entering lock-down. DQ
1
indicates lock-
down status and is set by the lock-down command. It cannot be cleared by software, only by device
reset or power-down.
3.2.6
Locking Operations during Erase Suspend
Changes to block lock status can be performed during an erase suspend by using the standard
locking command sequences to unlock, lock, or lock-down a block. This is useful in the case when
another block needs to be updated while an erase operation is in progress.
Table 4. Block Lock Status
Item
Address
Data
Block Lock Configuration
Block Base Address +002
LOCK
Block Is Unlocked
DQ
0
= 0
Block Is Locked
DQ
0
= 1
Block Is Locked-Down
DQ
1
= 1