AT25DF021 datasheet(30/41 Pages) ATMEL

30 / 41 page

3677D–DFLASH–04/09

AT25DF021

13. System Considerations

In an effort to continue our goal of maintaining world-class quality leadership, Atmel has been

performing extensive testing on the AT25DF021 that would not normally be done with a Serial

Flash device. The testing that has been performed on the AT25DF021 involved extensive, non-

stop reading of the memory array on pre-conditioned devices. The pre-conditioning of the

devices, which entailed erasing and programming the entire memory array 10,000 times, was

done to simulate a customer environment and to exercise the memory cells to a certain degree.

The non-stop reading of the devices was done in three levels of granularity, with the first level

involving a continuous, looped read of 256 bytes (a single page) of memory, the second level

involving a continuous, looped-read of a 4-Kbyte (16 pages) portion of memory, and the third

level entailing non-stop reading of the entire memory array. Read operations were performed at

both +25°C and +125°C and with a supply voltage of 3.7V, which exceeds the specified

datasheet operating voltage range.

The results of all of the extensive tests indicate that the contents of a portion of memory being

read continuously could be altered after 800,000,000 read operations only if that portion of the

memory was not erased or reprogrammed at all during the 800,000,000 read operations. If that

portion of memory was reprogrammed at some point, then it would take another 800,000,000

read operations after reprogramming before the contents could potentially be altered. For exam-

ple, if the Serial Flash is being used for boot code storage, then it would take 800,000,000 boot

operations before that boot code may become altered, provided that the boot code was not

updated or reprogrammed. If an application was to read the entire memory array non-stop at a

clock frequency of 10MHz, it would take over 5 years to reach 800,000,000 read operations.

Atmel firmly believes that this extended testing result should not be a cause for concern. We

also believe that most, if not all, applications will never read the same portion of memory

800,000,000 times throughout the life of the application without ever updating that portion of

memory.

AT25DF021 数据表(PDF) 30 Page - ATMEL Corporation