AT25DF641A datasheet(2/57 Pages) ATMEL

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8693A–DFLASH–8/10

Atmel AT25DF641A [Preliminary]

Description

The Atmel® AT25DF641 is a serial interface Flash memory device designed for use in a wide

variety of high-volume consumer based applications in which program code is shadowed from

Flash memory into embedded or external RAM for execution. The flexible erase architecture of

the AT25DF641A, with its erase granularity as small as 4-Kbytes, makes it ideal for data storage

as well, eliminating the need for additional data storage EEPROM devices.

The physical sectoring and the erase block sizes of the AT25DF641A have been optimized to

meet the needs of today's code and data storage applications. By optimizing the size of the

physical sectors and erase blocks, the memory space can be used much more efficiently.

Because certain code modules and data storage segments must reside by themselves in their

own protected sectors, the wasted and unused memory space that occurs with large sectored

and large block erase Flash memory devices can be greatly reduced. This increased memory

space efficiency allows additional code routines and data storage segments to be added while

still maintaining the same overall device density.

The AT25DF641A also offers a sophisticated method for protecting individual sectors against

erroneous or malicious program and erase operations. By providing the ability to individually pro-

tect and unprotect sectors, a system can unprotect a specific sector to modify its contents while

keeping the remaining sectors of the memory array securely protected. This is useful in applica-

tions where program code is patched or updated on a subroutine or module basis, or in

applications where data storage segments need to be modified without running the risk of errant

modifications to the program code segments. In addition to individual sector protection capabili-

ties, the AT25DF641A incorporates Global Protect and Global Unprotect features that allow the

entire memory array to be either protected or unprotected all at once. This reduces overhead

during the manufacturing process since sectors do not have to be unprotected one-by-one prior

to initial programming.

To take code and data protection to the next level, the AT25DF641A incorporates a sector lock-

down mechanism that allows any combination of individual 64-Kbyte sectors to be locked down

and become permanently read-only. This addresses the need of certain secure applications that

require portions of the Flash memory array to be permanently protected against malicious

attempts at altering program code, data modules, security information, or encryption/decryption

algorithms, keys, and routines. The device also contains a specialized OTP (One-Time Pro-

grammable) Security Register that can be used for purposes such as unique device

serialization, system-level Electronic Serial Number (ESN) storage, locked key storage, etc.

Specifically designed for use in 3V systems, the AT25DF641A supports read, program, and

erase operations with a supply voltage range of 2.7V to 3.6V. No separate voltage is required for

programming and erasing.

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