AT45DB ATMEL Corporation, AT45DB Datasheet - Page 17

• Manufacturer Part Number: AT45DB
• Description: 1-Megabit 2.7-volt Only Serial DataFlash
• Manufacturer: ATMEL Corporation

Figure 2. Algorithm for Randomly Modifying Data
Notes:
1.
2.
3.
To preserve data integrity, each page of a DataFlash
sector must be updated/rewritten at least once
within every 10,000 cumulative page erase/program
operations within that sector.
A Page Address Pointer must be maintained to indi-
cate which page is to be rewritten. The Auto Page
Rewrite command 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 10,000 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.
MAIN MEMORY PAGE PROGRAM
(82H)
to BUFFER TRANSFER
ADDRESS POINTER
MAIN MEMORY PAGE
Auto Page Rewrite
INCREMENT PAGE
START
(53H)
(58H)
END
provide address of
page to modify
Sector Addressing
MEMORY PAGE PROGRAM
(2)
PA8
(2)
0
0
1
BUFFER to MAIN
BUFFER WRITE
PA7
(84H)
(83H)
X
X
0
If planning to modify multiple
bytes currently stored within
a page of the Flash array
PA6
X
X
0
PA5
X
X
0
PA4
0
X
X
PA3
X
X
0
PA2-
PA0
X
X
X
Sector
0
1
2
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