256Mb: 3V Embedded Parallel NOR Flash
Device Protection
3. The NVPB lock bit is volatile and default to ‘1’ (NVPB bits unlocked) after power-up
and hardware reset. NVPB bits are locked by setting the NVPB lock bit to ‘0’. Once pro-
grammed to ‘0’, the NVPB lock bit can be reset to ‘1’ only be taking the device through a
power-up or hardware reset.
Figure 12: Software Protection Scheme
Volatile protection bit
Nonvolatile protection bit
1 = unprotected (default)
1 = unprotected
0 = protected
0 = protected
(Default setting depends on the product order option)
Volatile
protection
Nonvolatile
protection
Nonvolatile protection bit lock bit (volatile)
Array block
1 = unlocked (default, after power-up or hardware reset)
0 = locked
Nonvolatile protection
mode
Password protection
mode
1. Nonvolatile protection bits default to 1 (block unprotected) when the parts are first
shipped. A block is protected or unprotected when its nonvolatile protection bit is set to
0 and 1, respectively.
Notes:
2. Volatile protection bits are programmed and cleared individually. Nonvolatile protection
bits are programmed individually and cleared collectively.
3. Volatile protection bit default status depends on ordering option. A block is protected
or unprotected when its volatile protection bit is set to 0 and 1, respectively. For the vol-
atile protection to be effective, the block nonvolatile protection bit must be set to 1
(block unprotected).
4. Once programmed to 0, the nonvolatile protection bit lock bit can be reset to 1 only by
taking the device through a power-up or hardware reset.
PDF: 09005aef84ecabef
m29dw_256g.pdf - Rev. A 10/12 EN
Micron Technology, Inc. reserves the right to change products or specifications without notice.
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