M25PE40VMP6P datasheet(35/60 Pages) STMICROELECTRONICS

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M25PE40

Instructions

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6.11

Write to Lock Register (WRLR)

Note:

The Write to Lock Register (WRLR) instruction is decoded only in the in the T9HX process

(see Important note on page 6).

The Write to Lock Register (WRLR) instruction allows bits to be changed in the Lock

Registers. Before it can be accepted, a Write Enable (WREN) instruction must previously

have been executed. After the Write Enable (WREN) instruction has been decoded, the

device sets the Write Enable Latch (WEL).

The Write to Lock Register (WRLR) instruction is entered by driving Chip Select (S) Low,

followed by the instruction code, three address bytes (pointing to any address in the targeted

sector and one data byte on Serial Data Input (D). The instruction sequence is shown in

Figure 17. Chip Select (S) must be driven High after the eighth bit of the data byte has been

latched in, otherwise the Write to Lock Register (WRLR) instruction is not executed.

Lock Register bits are volatile, and therefore do not require time to be written. When the

Write to Lock Register (WRLR) instruction has been successfully executed, the Write

Enable Latch (WEL) bit is reset after a delay time less than tSHSL minimum value.

Any Write to Lock Register (WRLR) instruction, while an Erase, Program or Write cycle is in

progress, is rejected without having any effects on the cycle that is in progress.

Figure 17.

Write to Lock Register (WRLR) instruction sequence

Table 10.

Lock Register In(1)

The table rows in gray are true for products processed in the T7X process only (see Important note on

page 6).

Sector

Bit

Value

All sectors

b7-b2

‘0’

Sector Lock Down Bit Value

Sector Write Lock Bit Value

AI10784b

3456789 10

28 29 30 31 32 33 34 35

22 21

3210

36 37 38

Instruction

24-Bit Address

765432

Lock Register

Value

MSB

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