256Mb, 3V Multiple I/O Serial Flash Memory
Security Registers
Security Registers
Security registers enable sector and password protection on multiple levels using non-
volatile and volatile register and bit settings (shown below). The applicable register ta-
bles follow.
Figure 15: Sector and Password Protection
(See Note 1)
Sector Protection Register
15 14 13
Memory Sectors
Last sector
2
n
1
n
0
1
0
1
0
0
1
locked
locked
.
.
.
.
.
.
.
.
.
locked
1
3rd sector
2nd sector
1st sector
1
1
0
0
0
(See Note 2)
Global Freeze Bit
locked
(See Note 3)
(See Note 4)
n
Nonvolatile
Lock Bits
Volatile
Lock Bits
1. Sector protection register. This 16-bit nonvolatile register includes two active bits[2:1]
Notes:
to enable sector and password protection.
2. Global freeze bit. This volatile bit protects the settings in all nonvolatile lock bits.
3. Nonvolatile lock bits. Each nonvolatile bit corresponds to and provides nonvolatile
protection for an individual memory sector, which remains locked (protection enabled)
until its corresponding bit is cleared to 1.
4. Volatile lock bits. Each volatile bit corresponds to and provides volatile protection for
an individual memory sector, which is locked temporarily (protection is cleared when the
device is reset or powered down).
5. The first and last sectors will have volatile protections at the 4KB subsector level. Each
4KB subsector in these sectors can be individually locked by volatile lock bits setting;
nonvolatile protections granularity remain at the sector level.
CCMTD-1725822587-3368
mt25q-qljs-L256-ABA-xxT.pdf - Rev. K 07/18 EN
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34
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