31
AT45DB1282
2472C–DFLSH–11/03
Figure 2. Algorithm for Randomly Modifying Data
Notes: 1. To preserve data integrity, each page of a DataFlash sector must be updated/rewritten at least once within every 2,000
cumulative page erase/program operations.
2. A Page Address Pointer must be maintained to indicate which page is to be rewritten.
3. Other algorithms can be used to rewrite portions of the Flash array. Low-power applications may choose to wait until 2,000
cumulative page erase/program operations have accumulated before rewriting all pages of the sector. See application note
AN-4 (“Using Atmel’s Serial DataFlash”) for more details.
BUFFER WRITE
(84h, 87h)
PAGE ERASE
(81h)
BUFFER TO MAIN
MEMORY PAGE PROGRAM
(88h, 89h) or (98h, 99h)
START
MAIN MEMORY PAGE
TO BUFFER TRANSFER
(53h, 55h)
provide address of
page to modify
If planning to modify multiple
bytes currently stored within
a page of the Flash array
INCREMENT PAGE
ADDRESS POINTER
(2)
END
Sector Addressing
PA13 PA12 PA11 PA10 PA9 PA8 PA7 PA6 PA5 PA4 PA3 PA2 - PA0 Sector
00000000000 X 0
000000XXXXX X 1
000001XXXXX X 2
000010XXXXX X 3
••••••••••• • •
••••••••••• • •
••••••••••• • •
111100XXXXX X 61
111101XXXXX X 62
111110XXXXX X 63
111111XXXXX X 64
