MT28F322D20 Micron Technology, MT28F322D20 Datasheet - Page 25

• Manufacturer Part Number: MT28F322D20
• Description: (MT28F322D18 / MT28F322D20) FLASH MEMORY
• Manufacturer: Micron Technology

LOCKED DOWN STATE
tected from PROGRAM and ERASE operations, but their
protection status cannot be changed using software com-
mands 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.
input. 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
a software command to the [110] state, where they can be
erased and programmed. These blocks can then be
relocked [111] and unlocked [110] as desired while WP#
remains HIGH. When WP# goes LOW, blocks that were
previously locked down return to the locked down state
[011] regardless of any changes made while WP# was
HIGH. Device reset or power-down resets all locks, in-
cluding those in lock down, to locked state (see Table 12).
READING A BLOCK’S LOCK STATUS
device identification mode. To enter this mode, write 90h
to the bank containing address 00h. Subsequent READs
at block address +00002 will output the lock status of that
block. The lowest two outputs, DQ0 and DQ1, represent
the lock status. DQ0 indicates the block lock/unlock sta-
tus and is set by the LOCK command and cleared by the
2 Meg x 16 Async/Page/Burst Flash Memory
MT28F322D20FH_4.p65 – Rev. 4, Pub. 7/02
WP#
Blocks that are locked down (state [011]) are pro-
The LOCK DOWN function is dependent on the WP#
The lock status of every block can be read in the read
0
0
0
1
1
1
1
DQ1
0
0
1
0
0
1
1
DQ0
0
1
1
0
1
0
1
Locked (Default)
Lock Down
Lock Down
Lock Down
Unlocked
Unlocked
Disabled
Disabled
Locked
NAME
Block Locking State Transition
ERASE/PROG
Table 11
ALLOWED
ASYNC/PAGE/BURST FLASH MEMORY
Yes
Yes
Yes
No
No
No
No
25
UNLOCK command. It is also automatically set when
entering lock down. DQ1 indicates lock down status and
is set by the LOCK DOWN command. It can only be
cleared by reset or power-down, not by software. Table
11 shows the locking state transition scheme. The READ
ARRAY command, FFh, must be issued to the bank con-
taining address 00h prior to issuing other commands.
LOCKING OPERATIONS DURING ERASE SUSPEND
an ERASE SUSPEND by using the standard locking com-
mand sequences to unlock, lock, or lock down. This is
useful in the case when another block needs to be up-
dated while an ERASE operation is in progress.
first write the ERASE SUSPEND command (B0h), then
check the status register until it indicates that the ERASE
operation has been suspended. Next, write the desired
lock command sequence to block lock, and the lock sta-
tus will be changed. After completing any desired LOCK,
READ, or PROGRAM operations, resume the ERASE op-
eration with the ERASE RESUME command (D0h).
ERASE SUSPEND operation on the same block, the lock-
ing status bits will be changed immediately. Then, when
the ERASE is resumed, the ERASE operation will com-
plete.
PROGRAM SUSPEND.
Changes to block lock status can be performed during
To change block locking during an ERASE operation,
If a block is locked or locked down during an
A locking operation cannot be performed during a
Micron Technology, Inc., reserves the right to change products or specifications without notice.
No Change
No Change
No Change
No Change
To [001]
To [101]
To [111]
LOCK
No Change
No Change
No Change
No Change
UNLOCK
To [000]
To [100]
To [110]
2 MEG x 16
©2002, Micron Technology, Inc.
No Change
No Change
To [011]
To [011]
To [111]
To [111]
To [111]
DOWN
LOCK