M25PX16 Serial Flash Embedded Memory
WRITE to LOCK REGISTER
WRITE to LOCK REGISTER
The WRITE to LOCK REGISTER instruction allows the lock register bits to be changed.
Before the WRITE to LOCK REGISTER instruction can be accepted, a WRITE ENABLE
instruction must have been executed previously. After the WRITE ENABLE instruction
has been decoded, the device sets the write enable latch (WEL) bit.
The WRITE to LOCK REGISTER instruction is entered by driving chip select (S#) LOW,
followed by the instruction code, three address bytes, and one data byte on serial data
input (DQ0). The address bytes must point to any address in the targeted sector. S#
must be driven HIGH after the eighth bit of the data byte has been latched in. Otherwise
the WRITE to LOCK REGISTER instruction is not executed.
Lock register bits are volatile, and therefore do not require time to be written. When the
WRITE to LOCK REGISTER instruction has been successfully executed, the WEL bit is
reset after a delay time of less than tSHSL minimum value.
Any WRITE to LOCK REGISTER instruction issued while an ERASE, PROGRAM, or
WRITE cycle is in progress is rejected without any effect on the cycle that is in progress.
Figure 23: WRITE to LOCK REGISTER Instruction Sequence
0
7
8
Cx
C
LSB
A[MIN]
LSB
DIN
DIN
DIN
DIN
DIN
DIN
DIN
DIN
DIN
DQ[0]
Command
MSB
A[MAX]
MSB
1. Cx = 7 + (A[MAX] + 1).
Note:
Table 11: Lock Register In
Sector
Bit
Value
All sectors
All sectors
All sectors
b7–b2
b1
0
Sector lock-down bit value
Sector write lock bit value
b0
Note: Values of b1 and b0 after power-up are defined in Power-Up/Down and Supply
Line Decoupling (page 41). For the sector lock down and sector write lock values, see
the Lock Register Out table in READ LOCK REGISTER (page 29).
PDF: 09005aef845665a5
m25px16.pdf - Rev. A 11/12 EN
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