2 write disable – Rainbow Electronics AT25DF081A User Manual
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8715C–SFLSH–11/2012
AT25DF081A
9.2
Write Disable
The Write Disable command is used to reset the Write Enable Latch (WEL) bit in the Status Register to the logical
"0" state. With the WEL bit reset, all Byte/Page Program, erase, Protect Sector, Unprotect Sector, Sector Lock-
down, Freeze Sector Lockdown State, Program OTP Security Register, and Write Status Register commands will
not be executed. Other conditions can also cause the WEL bit to be reset; for more details, refer to the WEL bit
section of the Status Register description.
To issue the Write Disable command, the CS pin must first be asserted and the opcode of 04h must be clocked
into the device. No address bytes need to be clocked into the device, and any data clocked in after the opcode will
be ignored. When the CS pin is deasserted, the WEL bit in the Status Register will be reset to a logical “0”. The
complete opcode must be clocked into the device before the CS pin is deasserted, and the CS pin must be deas-
serted on an even byte boundary (multiples of eight bits); otherwise, the device will abort the operation and the
state of the WEL bit will not change.
Figure 9-2.
Write Disable
SCK
CS
SI
SO
MSB
2
3
1
0
0
0
0
0
0
1
0
0
6
7
5
4
OPCODE
HIGH-IMPEDANCE