AT25DF641_13 datasheet(17/56 Pages) ETC2

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AT25DF641

3680F–DFLASH–4/10

Figure 7-6.

Chip Erase

SCK

MS B

OP C ODE

HIG H-IMP E DANC E

7.5.

Program/Erase Suspend

In some code plus data storage applications, it is often necessary to process certain high-level system interrupts

that require relatively immediate reading of code or data from the Flash memory. In such an instance, it may not

be possible for the system to wait the microseconds or milliseconds required for the Flash memory to complete a

program or erase cycle. The Program/Erase Suspend command allows a program or erase operation in progress

to a particular 64-Kbyte sector of the Flash memory array to be suspended so that other device operations can be

performed. For example, by suspending an erase operation to a particular sector, the system can perform

functions such as a program or read operation within another 64-Kbyte sector in the device. Other device

operations, such as a R ead Status Register, can also be p erformed while a program or erase operation is

suspended. Table 7-1 outlines the operations that are allowed and n ot allowed during a pr ogram or erase

suspend.

Since the need to suspend a program or erase operation is immediate, the Write Enable command does not need

to be issued prior to the Program/Erase Suspend command being issued. Therefore, the Program/Erase Suspend

command operates independently of the state of the WEL bit in the Status Register.

To perform a Program/Erase Suspend, the

pin must first be asserted and the opcode of B0h 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 program or erase operation currently in progress will be

suspended within a time of tSUSP. The Program Suspend (PS) bit or the Erase Suspend (ES) bit in the Status

suspended. In addition, the RDY/BSY bit in the Status Register will indicate that the device is ready for another

operation. The complete opcode must be clocked into the device before the

pin is deasserted, and the

must be deasserted on an even byte boundary (multiples of eight bits); otherwise, no suspend operation will be

performed.

Read operations are not allowed to a 64-Kbyte sector that has had its program or erase operation suspended. If a

read is attempted to a suspended sector, then the device will output undefined data. Therefore, when performing

a Read Array operation to an uns uspended sector and the device’s internal address counter increments and

crosses the sector boundary to a suspended sector, the device will then start outputting undefined data

continuously until the address counter increments and crosses a sector boundary to an unsuspended sector.

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