GD25LE256DWJS datasheet(54/83 Pages) GIGADEVICE

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1.8V Uniform Sector

Dual and Quad Serial Flash

GD25LE256D

7.31. Erase Security Registers (44H)

The GD25LE256D provides two 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 

CS# goes high. The command sequence is shown in Figure33. 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

(LB2-3) 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 #2

00H

0 0 1 0

0 0

Don

’t care

Security Register #3

00H

0 0 1 1

0 0

Don

’t care

Figure33. Erase Security Registers command Sequence Diagram

Command

44H

CS#

SCLK

29 30 31

MSB

24 Bits Address

23 22

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