256Mb, 3V Multiple I/O Serial Flash Memory
Nonvolatile and Volatile Sector Lock Bits Security
Nonvolatile and Volatile Sector Lock Bits Security
Table 15: Nonvolatile and Volatile Lock Bits
Bit
Details
Nonvolatile Lock Bit
Volatile Lock Bit
Description Each sector of memory has one corresponding non-
volatile lock bit
Each sector of memory has one corresponding vola-
tile lock bit; this bit is the sector write lock bit descri-
bed in the Volatile Lock Bit Register table.
Function
When set to 0, locks and protects its corresponding
When set to 1, locks and protects its corresponding
memory sector from PROGRAM or ERASE operations. memory sector from PROGRAM or ERASE operations.
Because this bit is nonvolatile, the sector remains Because this bit is volatile, protection is temporary.
locked, protection enabled, until the bit is cleared to The sector is unlocked, protection disabled, upon de-
1.
vice reset or power-down.
Settings
1 = Lock disabled
0 = Lock enabled
0 = Lock disabled
1 = Lock enabled
Enabling
The bit is set to 0 by the WRITE NONVOLATILE LOCK The bit is set to 1 by the WRITE VOLATILE LOCK BITS
protection BITS command, enabling protection for designated
locked sectors. Programming a sector lock bit re-
quires the typical byte programming time.
command, enabling protection for designated locked
sectors.
Disabling
All bits are cleared to 1 by the ERASE NONVOLATILE All bits are set to 0 upon reset or power-down, un-
protection LOCK BITS command, unlocking and disabling pro-
tection for all sectors simultaneously. Erasing all sec-
tor lock bits requires typical sector erase time.
locking and disabling protection for all sectors.
Reading
the bit
Bits are read by the READ NONVOLATILE LOCK BITS Bits are read by the READ VOLATILE LOCK BITS com-
command. mand.
Volatile Lock Bit Security Register
One volatile lock bit register is associated with each sector of memory. It enables the
sector to be locked, unlocked, or locked-down with the WRITE VOLATILE LOCK BITS
command, which executes only when sector lock down (bit 1) is set to 0. Each register
can be read with the READ VOLATILE LOCK BITS command. This register is compatible
with and provides the same locking capability as the lock register in the Micron N25Q
SPI NOR family.
Table 16: Volatile Lock Bit Register
Bit Name
Settings
Description
7:2 Reserved
0
Bit values are 0.
1
0
Sector
0 = Lock-down disabled (Default) Volatile bit: Device always powers up with this bit set to 0 so that
lock down 1 = Lock-down enabled
sector lock down and sector write lock bits can be set to 1. When
this bit set to 1, neither of the two volatile lock bits can be written
to until the next power cycle, hardware, or software reset.
Sector
0 = Write lock disabled (Default) Volatile bit: Device always powers up with this bit set to 0 so that
write lock 1 = Write lock enabled
PROGRAM and ERASE operations in this sector can be executed
and sector content modified. When this bit is set to 1, PROGRAM
and ERASE operations in this sector are not executed.
CCMTD-1725822587-3368
mt25q-qljs-L256-ABA-xxT.pdf - Rev. K 07/18 EN
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