AT25DF081A datasheet(16/54 Pages) ETC2

16 / 54 page

8715C–SFLSH–1/2013

AT25DF081A

8.4

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 previously 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 functional-

ity 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 or locked down 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 Sta-

tus Register will be reset back to the logical “0” state if the CS pin is deasserted on uneven byte boundaries or if a

sector is in the protected or locked down 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 Register be polled rather than waiting the

tCHPE 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 erase algorithm that can detect when a byte location fails to erase prop-

erly. If an erase error occurs, it will be indicated by the EPE bit in the Status Register.

Figure 8-6.

Chip Erase

SCK

MSB

CCCCCCCC

OPCODE

HIGH-IMPEDANCE

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