The Atmel® AT25DF081A is a serial interface Flash memory device designed for use in a wide variety of high-vol-
ume 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 AT25DF081A, 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
The physical sectoring and the erase block sizes of the AT25DF081A 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 AT25DF081A also offers a sophisticated method for protecting individual sectors against erroneous or mali-
cious 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
AT25DF081A 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 AT25DF081A incorporates a sector lockdown 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 per-
manently 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 3-volt systems, the AT25DF081A 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.
2 Atmel AT25DF081A [Preliminary]