The AT25DF641A is a 2.7V minimum, serial-interface Flash memory ideally suited for 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
4KB, 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 protect 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 applications 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 capabilities, 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 lockdown mechanism that
allows any combination of individual 64KB 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
Programmable) Security Register that can be used for purposes such as unique device serialization, system-level
Electronic Serial Number (ESN) storage, locked key storage, or other purposes.
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.