14

3599F–DFLASH–09/06

AT26DF161

issue the Unprotect Sector command will be ignored, and the device will reset the WEL bit in the

Status Register back to a logical “0” and return to the idle state once the CS pin has been

deasserted.

Figure 9-4.

Unprotect Sector

9.5

Global Protect/Unprotect

The Global Protect and Global Unprotect features can work in conjunction with the Protect Sec-

tor and Unprotect Sector functions. For example, a system can globally protect the entire

memory array and then use the Unprotect Sector command to individually unprotect certain sec-

tors and individually reprotect them later by using the Protect Sector command. Likewise, a

system can globally unprotect the entire memory array and then individually protect certain sec-

tors as needed.

Performing a Global Protect or Global Unprotect is accomplished by writing a certain combina-

tion of data to the Status Register using the Write Status Register command (see “Write Status

Register” section on page 21 for command execution details). The Write Status Register com-

mand is also used to modify the SPRL (Sector Protection Registers Locked) bit to control

hardware and software locking.

To perform a Global Protect, the appropriate WP pin and SPRL conditions must be met and the

system must write a logical “1” to bits 5, 4, 3, and 2 of the Status Register. Conversely, to per-

form a Global Unprotect, the same WP and SPRL conditions must be met but the system must

write a logical “0” to bits 5, 4, 3, and 2 of the Status Register. Table 9-2 details the conditions

necessary for a Global Protect or Global Unprotect to be performed.

SCK

CS

SI

SO

MSB

MSB

23

1

0

00111001

67

5

410 11

9

812

31

29 30

27 28

26

OPCODE

AAAA

AAA

A

A

A

A

A

ADDRESS BITS A23-A0

HIGH-IMPEDANCE