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AT25DF641

3680F–DFLASH–4/10

Figure 7-8.

Program/Erase Resume

SCK

MS B

OP C ODE

HIG H-IMP E DANC E

Protection Commands and Features

8.1.

Write Enable

The Write Enable command is used to set the Write Enable Latch (WEL) bit in the Status Register to a logical “1”

state. The WEL bit must be set before a Byte/Page Program, erase, Protect Sector, Unprotect Sector, Sector

Lockdown, Freeze Sector Lockdown State, Program OTP Security Register, or Write Status Register command

can be executed. This makes the issuance of these commands a two step process, thereby reducing the chances

of a command being accidentally or erroneously executed. If the WEL bit in the Status Register is not set prior to

the issuance of one of these commands, then the command will not be executed.

To issue the Write Enable command, the

pin must first be asserted and the opcode of 06h 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

pin is deasserted, the WEL bit in the Status Register will be set to a logical “1”. The

complete opcode must be clocked into the device before the

pin is deasserted, and the

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 8-1.

Write Enable

SCK

MS B

OP C ODE

HIG H-IMP E DANC E

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