AT45D041

15

Algorithm for Randomly Modifying Data

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

(82H, 85H)

BUFFER WRITE

(84H, 87H)

BUFFER to MAIN

MEMORY PAGE PROGRAM

(83H, 86H)

Figure 2

Notes:

1.

To preserve data integrity, each page of the DataFlash memory array must be updated/rewritten at least once within

every 10,000 cumulative page erase/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.

3.

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

10,000 cumulative page erase/program operations have accumulated before rewriting all pages of the Flash array. See

application note AN-4 (“Using Atmel’s Serial DataFlash”) for more details.