AT45DB321D datasheet(42/52 Pages) ETC2

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AT45DB321D [DATASHEET]

3597T–DFLASH–11/2013

Figure 23-2. Algorithm for Randomly Modifying Data

Notes: 1.

To preserve data integrity, each page of an DataFlash sector must be updated/rewritten at least once within every

20,000 cumulative page erase and program operations.

2. A page address pointer must be maintained to indicate which page is to be rewritten. The auto page rewrite com-

mand must use the address specified by the page address pointer.

Other algorithms can be used to rewrite portions of the flash array. Low-power applications may choose to wait

until 20,000 cumulative page erase and program operations have accumulated before rewriting all pages of the

sector. See application note AN-4 (“Using Serial DataFlash”) for more details.

START

Main Memory Page

to Buffer Transfer

(53h, 55h)

Increment Page

Address Pointer

(2)

Auto Page Rewrite

(2)

(58h, 59h)

END

provide address of

page to modify

If planning to modify multiple

bytes currently stored within

a page of the Flash array

Main Memory Page Program

through Buffer

(82h, 85h)

Buffer Write

(84h, 87h)

Buffer to Main

Memory Page Program

(83h, 86h)

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