1. Description
The AT25DQ161 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
AT25DQ161, 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 AT25DQ161 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 m emory 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 AT25 DQ161 also offers a sop histica ted me thod for protecting individual sectors ag ainst
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-
tion s whe re p rogram co de is pa tch ed o r up dat ed on a su bro utine or mo dule 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 AT25DQ161 incorporates Global Protect and Global Unprotect features that allow the
entire m emory array to b e eithe r protected or unprotected all at on ce. This red uces 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 AT25DQ161 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 p ortions of the Flash m emory ar ray to be pe rman ently p rotected against malicio us
attempts at altering program code, data modules, security information, or encryption/decryption
algorithms, ke ys, an d routines. The device also contains a specialized OTP ( One-Time Pro-
gr amm able) Se curity Register th at can be used for purpo ses such as un ique device
serialization, system-level Electronic Serial Number (ESN) storage, locked key storage, etc.
Specifically designed for use in 3-vo lt syste ms, the AT2 5DQ161 sup ports read, pr ogram, and
erase operations with a supply voltage range of 2.7V to 3.6V. No separate voltage is required for
programming and erasing.
2 AT25DQ161 [Preliminary]
8671A–DFLASH–07/09
