W25Q40BLSVIP datasheet(56/74 Pages) WINBOND

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W25Q40BL

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7.2.38 Program Security Registers (42h)

The Program Security Register instruction is similar to the Page Program instruction. It allows from one

byte to 256 bytes of security register data to be programmed at previously erased (FFh) memory locations.

A Write Enable instruction must be executed before the device will accept the Program Security Register

Instruction (Status Register bit WEL= 1). The instruction is initiated by driving the /CS pin low then shifting

the instruction code “42h” followed by a 24-bit address (A23-A0) and at least one data byte, into the DI pin.

The /CS pin must be held low for the entire length of the instruction while data is being sent to the device.

ADDRESS

A23-16

A15-12

A11-8

A7-0

Security Register #1

00h

0 0 0 1

0 0 0 0

Byte Address

Security Register #2

00h

0 0 1 0

0 0 0 0

Byte Address

Security Register #3

00h

0 0 1 1

0 0 0 0

Byte Address

The Program Security Register instruction sequence is shown in figure 36. The Security Register Lock

Bits LB[3:1] in the Status Register-2 can be used to OTP protect the security registers. Once a lock bit is

set to 1, the corresponding security register will be permanently locked, Program Security Register

instruction to that register will be ignored (See 7.1.9, 7.2.21 for detail descriptions).

Figure 36. Program Security Registers Instruction Sequence

Instruction (42h)

W25Q40BLSVIP Datasheet(PDF) 56 Page - Winbond