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AT25DF641A [DATASHEET]

8793F–DFLASH–11/2017

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 Lockdown, 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, see Section 11.1.5, “WEL Bit” on page 37 in

“Status Register Commands” .

To issue the Write Disable command, the CS pin must first be asserted and then the opcode 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 deasserted 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

MSB

00000100

Opcode

High-impedance

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