M25PE80
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Read Lock Register (RDLR)
The device is first selected by driving Chip Select
(S) Low. The instruction code for the Read Lock
Register (RDLR) instruction is followed by a 3-
Byte address (A23-A0) pointing to any location in-
side the concerned sector (or sub-sector). Each
address bit is latched-in during the rising edge of
Serial Clock (C). Then the value of the Lock Reg-
ister is shifted out on Serial Data Output (Q), each
bit being shifted out, at a maximum frequency f
C
,
during the falling edge of Serial Clock (C).
The instruction sequence is shown in
Figure 14.
The Read Lock Register (RDLR) instruction is ter-
minated by driving Chip Select (S) High at any
time during data output.
Any Read Lock Register (RDLR) instruction, while
an Erase, Program or Write cycle is in progress, is
rejected without having any effects on the cycle
that is in progress.
Table 8. Lock Register Out
Note: 1. Valid only for sector 0 and sector 15 (the value ‘0’ is returned for other sectors).
Figure 14. Read Lock Register (RDLR) Instruction Sequence and Data-Out Sequence
Bit
Bit Name
Value
Function
b7-b4
Reserved
b3
Sub-sector Lock Down
(1)
‘1’
The Write Lock and Lock Down Bits cannot be changed Once a ‘1’ is
written to the Lock Down Bit it cannot be cleared to ‘0’ except by a
Reset or power-up.
‘0’
The Write Lock and Lock Down Bits can be changed by writing new
values to them. (Default value).
b2
Sub-sector Write Lock
(1)
‘1’
Write, Program and Erase operations in this sub-sector will not be
executed. The memory contents will not be changed.
‘0’
Write, Program and Erase operations in this sub-sector are executed
and will modify the sub-sector contents. (Default value).
b1
Sector Lock Down
‘1’
The Write Lock and Lock Down Bits cannot be changed. Once a ‘1’ is
written to the Lock Down Bit it cannot be cleared to ‘0’, except by a
Reset or power-up.
‘0’
The Write Lock and Lock Down Bits can be changed by writing new
values to them. (Default value).
b0
Sector Write Lock
‘1’
Write, Program and Erase operations in this sector will not be
executed. The memory contents will not be changed.
‘0’
Write, Program and Erase operations in this sector are executed and
will modify the sector contents. (Default value).
C
D
AI10783
S
Q
23
2
1
3
4
5
6
7
8
9 10
28 29 30 31 32 33 34 35
22 21
3
2
1
0
36 37 38
7
6
5
4
3
1
0
High Impedance
Lock Register Out
Instruction
24-Bit Address
0
MSB
MSB
2
39