ACE25AB400G

Serial NOR Flash Memory 4M bits 3.0V Dual I/O Serial Flash Memory with 4KB Uniform Sector

VER 1.1

25

Program Security Registers (42H)

The Program Security Registers command is similar to the Page Program command. It allows from 1 to

256 bytes Security Registers data to be programmed. A Write Enable (WREN) command must previously

have been executed to set the Write Enable Latch (WEL) bit before sending the Program Security

Registers command. The Program Security Registers command is entered by driving CS# Low, followed

by the command code (42H), three address bytes and at least one data byte on SI. As soon as CS# is

driven high, the self-timed Program Security Registers cycle (whose duration is tPP) is initiated. While the

Program Security Registers cycle is in progress, the Status Register may be read to check the value of

the Write In Progress (WIP) bit. The Write In Progress (WIP) bit is 1 during the self-timed Program

Security Registers cycle, and is 0 when it is completed. At some unspecified time before the cycle is

completed, the Write Enable Latch (WEL) bit is reset.

If the Security Registers Lock Bit (LB) is set to 1, the Security Registers will be permanently locked.

Program Security Registers command will be ignored.

Address

A23-A16

A15-A8

A7-A0

Security Registers 0

00H

00H

Byte Address

Security Registers 1

00H

01H

Byte Address

Figure23. Program Security Registers command Sequence Diagram