22

3599F–DFLASH–09/06

AT26DF161

Unprotect should be performed, and two additional don’t care bits (see Table 10-2). Any addi-

tional data bytes that are sent to the device will be ignored. When the CS pin is deasserted, the

SPRL bit in the Status Register will be modified and the WEL bit in the Status Register will be

reset back to a logical “0”. The values of bits 5, 4, 3, and 2 and the state of the SPRL bit before

the Write Status Register command was executed (the prior state of the SPRL bit) will determine

whether or not a Global Protect or Global Unprotect will be perfomed. Please refer to the “Global

Protect/Unprotect” section on page 14 for more details.

The complete one byte of data must be clocked into the device before the CS pin is deasserted;

otherwise, the device will abort the operation, the state of the SPRL bit will not change, no

potential Global Protect or Unprotect will be performed, and the WEL bit in the Status Register

will be reset back to the logical “0” state.

If the WP pin is asserted, then the SPRL bit can only be set to a logical “1”. If an attempt is made

to reset the SPRL bit to a logical “0” while the WP pin is asserted, then the Write Status Register

command will be ignored, and the WEL bit in the Status Register will be reset back to the logical

“0” state. In order to reset the SPRL bit to a logical “0”, the WP pin must be deasserted.

Figure 10-2. Write Status Register

Table 10-2.

Write Status Register Format

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

SPRL

X

Global Protect/Unprotect

X

X

SCK

CS

SI

SO

MSB

23

1

0

0000000

67

5

410 11

9

8

14 15

13

12

OPCODE

MSB

1D

X

D

D

D

D

X

X

STATUS REGISTER IN

HIGH-IMPEDANCE