256Mb: 3V Embedded Parallel NOR Flash
Registers
Lock Register
Table 12: Lock Register Bit Definitions
Note 1 applies to entire table
Bit
Name
Settings
Description
Notes
DQ[15:5] RFU
–
Reserved for future use
2
DQ4
Volatile
lock
Programmable
Sets default values for volatile block protection; when this
bit is programmed, blocks are protected at power-up.
boot bit
DQ3
DQ2
RFU
–
Reserved for future use
2
3
Password
0 = Password protection
Places the device permanently in password protection mode.
protection mode enabled
mode lock 1 = Password protection
bit
mode disabled (Default)
DQ1
DQ0
Nonvolatile 0 = Nonvolatile protection Places the device in nonvolatile protection mode with pass-
protection mode enabled with pass- word protection mode permanently disabled. When shipped
3
mode lock word protection mode
from the factory, the device will operate in nonvolatile pro-
tection mode, and the memory blocks are unprotected.
bit
permanently disabled
1 = Nonvolatile protection
mode enabled (Default)
Extended
memory
block
protection
bit
0 = Protected
If the device is shipped with the extended memory block un-
1 = Unprotected (Default) locked, the block can be protected by setting this bit to 0.
The extended memory block protection status can be read in
auto select mode by issuing an AUTO SELECT command. It
can also be read by applying VID to A9.
1. The lock register is a 16-bit, one-time programmable register.
Notes:
2. DQ[15:5] and DQ[3] are reserved and are set to a default value of 1. During program-
ming, they must be held to 1.
3. The password protection mode lock bit and nonvolatile protection mode lock bit cannot
both be programmed to 0. Any attempt to program one while the other is programmed
causes the operation to abort, and the device returns to read mode. The device is ship-
ped from the factory with the default setting.
Table 13: Block Protection Status
Nonvolatile
Nonvolatile
Volatile
Block
Protection Bit Protection Protection Protection
Lock Bit1
Bit2
Bit3
Status
Block Protection Status
0
0
X
01h
Block protected by nonvolatile protection bit; nonvolatile
protection bit unchangeable.
0
0
1
1
1
0
00h
01h
Block unprotected; nonvolatile protection bit unchangeable.
Block protected by volatile protection bit; nonvolatile protec-
tion bit unchangeable.
1
1
0
1
X
0
01h
01h
Block protected by nonvolatile protection bit; nonvolatile
protection bit changeable.
Block protected by volatile protection bit; nonvolatile protec-
tion bit changeable.
PDF: 09005aef84ecabef
m29dw_256g.pdf - Rev. A 10/12 EN
Micron Technology, Inc. reserves the right to change products or specifications without notice.
25
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