AT25DF321 datasheet(11/37 Pages) ATMEL

11 / 37 page

3669B–DFLASH–6/09

AT25DF321

If the address specified by A23-A0 points to a memory location within a sector that is in the pro-

tected state, then the Block Erase command will not be executed, and the device will return to

the idle state once the CS pin has been deasserted.

The WEL bit in the Status Register will be reset back to the logical “0” state if the erase cycle

aborts due to an incomplete address being sent or because a memory location within the region

to be erased is protected.

While the device is executing a successful erase cycle, the Status Register can be read and will

indicate that the device is busy. For faster throughput, it is recommended that the Status Regis-

ter be polled rather than waiting the tBLKE time to determine if the device has finished erasing. At

some point before the erase cycle completes, the WEL bit in the Status Register will be reset

back to the logical “0” state.

The device also incorporates an intelligent erasing algorithm that can detect when a byte loca-

tion fails to erase properly. If an erase error arises, it will be indicated by the EPE bit in the

Status Register.

Figure 8-3.

Block Erase

8.3

Chip Erase

The entire memory array can be erased in a single operation by using the Chip Erase command.

Before a Chip Erase command can be started, the Write Enable command must have been pre-

viously issued to the device to set the WEL bit of the Status Register to a logical “1” state.

Two opcodes, 60h and C7h, can be used for the Chip Erase command. There is no difference in

device functionality when utilizing the two opcodes, so they can be used interchangeably. To

perform a Chip Erase, one of the two opcodes (60h or C7h) must be clocked into the device.

Since the entire memory array is to be erased, 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 device will erase the entire memory array. The erasing of the device is internally self-timed

and should take place in a time of tCHPE.

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, no

erase will be performed. In addition, if any sector of the memory array is in the protected state,

then the Chip Erase command will not be executed, and the device will return to the idle state

once the CS pin has been deasserted. The WEL bit in the Status Register will be reset back to

the logical “0” state if a sector is in the protected state.

While the device is executing a successful erase cycle, the Status Register can be read and will

indicate that the device is busy. For faster throughput, it is recommended that the Status Regis-

SCK

MSB

CCCCCCCC

410 11

812

29 30

27 28

OPCODE

AAAA

AAA

ADDRESS BITS A23-A0

HIGH-IMPEDANCE

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