AT25DF021 datasheet(2/41 Pages) ATMEL

2 / 41 page

3677D–DFLASH–04/09

AT25DF021

The physical sectoring and the erase block sizes of the AT25DF021 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 AT25DF021 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 AT25DF021 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.

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, etc.

Specifically designed for use in 2.5-volt or 3-volt systems, the AT25DF021 supports read, pro-

gram, and erase operations with a supply voltage range of 2.3V to 3.6V or 2.7V to 3.6V. No

separate voltage is required for programming and erasing.

AT25DF021 Folha de dados(PDF) 2 Page - ATMEL Corporation