SST25VF040B-50-4I-SAE SST [Silicon Storage Technology, Inc], SST25VF040B-50-4I-SAE Datasheet - Page 18

• Manufacturer Part Number: SST25VF040B-50-4I-SAE
• Description: 4 Mbit SPI Serial Flash
• Manufacturer: SST [Silicon Storage Technology, Inc]

Data Sheet
Write-Disable (WRDI)
The Write-Disable (WRDI) instruction resets the Write-
Enable-Latch bit and AAI bit to 0 disabling any new Write
operations from occurring. The WRDI instruction will not
Enable-Write-Status-Register (EWSR)
The Enable-Write-Status-Register (EWSR) instruction
arms the Write-Status-Register (WRSR) instruction and
opens the status register for alteration. The Write-Status-
Register instruction must be executed immediately after the
execution of the Enable-Write-Status-Register instruction.
This two-step instruction sequence of the EWSR instruc-
tion followed by the WRSR instruction works like SDP (soft-
ware data protection) command structure which prevents
any accidental alteration of the status register values. CE#
must be driven low before the EWSR instruction is entered
and must be driven high before the EWSR instruction is
executed.
©2009 Silicon Storage Technology, Inc.
FIGURE 17: Write Enable (WREN) Sequence
FIGURE 18: Write Disable (WRDI) Sequence
SCK
CE#
SCK
CE#
SO
SO
SI
SI
MODE 3
MODE 0
MODE 3
MODE 0
HIGH IMPEDANCE
HIGH IMPEDANCE
MSB
0 1 2 3 4 5 6 7
MSB
0 1 2 3 4 5 6 7
18
terminate any programming operation in progress. Any pro-
gram operation in progress may continue up to T
executing the WRDI instruction. CE# must be driven high
before the WRDI instruction is executed.
04
06
1295 WRDI.0
1295 WREN.0
4 Mbit SPI Serial Flash
SST25VF040B
S71295-05-000
BP
after
10/09