256Mb, 3V Multiple I/O Serial Flash Memory
Sector Protection Security Register
Sector Protection Security Register
Table 13: Sector Protection Register
Bits Name
Settings
Description
Notes
15:3 Reserved
1 = Default
–
2
Password
protection
lock
1 = Disabled (Default)
0 = Enabled
Nonvolatile bit: When set to 1, password protection is dis-
abled. When set to 0, password protection is enabled per-
manently; the 64-bit password cannot be retrieved or reset.
1, 2
1
Sector
protection
lock
1 = Enabled, with password
protection (Default)
0 = Enabled, without pass-
word protection
Nonvolatile bit: When set to 1, nonvolatile lock bits can
be set to lock/unlock their corresponding memory sectors;
bit 2 can be set to 0, enabling password protection perma-
nently.
1, 3, 4
When set to 0, nonvolatile lock bits can be set to lock/
unlock their corresponding memory sectors; bit 2 must re-
main set to 1, disabling password protection permanently.
0
Reserved
1 = Default
–
1. Bits 2 and 1 are user-configurable, one-time-programmable, and mutually exclusive in
that only one of them can be set to 0. It is recommended that one of the bits be set to 0
when first programming the device.
Notes:
2. The 64-bit password must be programmed and verified before this bit is set to 0 because
after it is set, password changes are not allowed, thus providing protection from mali-
cious software. When this bit is set to 0, a 64-bit password is required to reset the global
freeze bit from 0 to 1. In addition, if the password is incorrect or lost, the global freeze
bit can no longer be set and nonvolatile lock bits cannot be changed. (See the Sector
and Password Protection figure and the Global Freeze Bit Definition table).
3. Whether this bit is set to 1 or 0, it enables programming or erasing nonvolatile lock bits
(which provide memory sector protection). The password protection bit must be set be-
forehand because setting this bit will either enable password protection permanently
(bit 2 = 0) or disable password protection permanently (bit 1 = 0).
4. By default, all sectors are unlocked when the device is shipped from the factory. Sectors
are locked, unlocked, read, or locked down as explained in the Nonvolatile and Volatile
Lock Bits table and the Volatile Lock Bit Register Bit Definitions table.
Table 14: Global Freeze Bit
Bits Name
Settings
Description
7:1
0
Reserved
0
Bit values are 0
Global
freeze bit
1 = Disabled
(Default)
0 = Enabled
Volatile bit: When set to 1, all nonvolatile lock bits can be set to enable or
disable locking their corresponding memory sectors.
When set to 0, nonvolatile lock bits are protected from PROGRAM or ERASE
commands. This bit should not be set to 0 until the nonvolatile lock bits are
set.
1. The READ GLOBAL FREEZE BIT command enables reading this bit. When password pro-
tection is enabled, this bit is locked upon device power-up or reset. It cannot be
changed without the password. After the password is entered, the UNLOCK PASSWORD
command resets this bit to 1, enabling programing or erasing the nonvolatile lock bits.
After the bits are changed, the WRITE GLOBAL FREEZE BIT command sets this bit to 0,
protecting the nonvolatile lock bits from PROGRAM or ERASE operations.
Note:
CCMTD-1725822587-3368
mt25q-qljs-L256-ABA-xxT.pdf - Rev. K 07/18 EN
Micron Technology, Inc. reserves the right to change products or specifications without notice.
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