GD25LB64CSIS datasheet(47/70 Pages) GIGADEVICE

47 / 70 page

1.8V Uniform Sector

Dual and Quad Serial Flash

GD25LB64C

7.29 Erase Security Registers (44H)

The GD25LB64C provides three 1024-byte Security Registers which can be erased and programmed individually.

These registers may be used by the system manufacturers to store security and other important information separately

from the main memory array.

The Erase Security Registers command is similar to Sector/Block Erase command. A Write Enable (WREN)

command must previously have been executed to set the Write Enable Latch (WEL) bit.

The Erase Security Registers command sequence: CS# goes low  sending Erase Security Registers command 

3-Byte address on SI  CS# goes high. The command sequence is shown in Figure31. CS# must be driven high after the

eighth bit of the last address Byte has been latched in; otherwise the Erase Security Registers command is not executed.

As soon as CS# is driven high, the self-timed Erase Security Registers cycle (whose duration is tSE) is initiated. While the

Erase 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 Erase 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. The Security

Registers Lock Bit (LB3-1) in the Status Register can be used to OTP protect the security registers. Once the LB bit is set

to 1, the Security Registers will be permanently locked; the Erase Security Registers command will be ignored.

Address

A23-16

A15-12

A11-10

A9-0

Security Register #1

00H

0 0 0 1

0 0

Don

’t care

Security Register #2

00H

0 0 1 0

0 0

Don

’t care

Security Register #3

00H

0 0 1 1

0 0

Don

’t care

Figure31. Erase Security Registers command Sequence Diagram

Command

44H

CS#

SCLK

29 30 31

MSB

24 Bits Address

23 22

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