at45db021b ATMEL Corporation, at45db021b Datasheet - Page 26

• Manufacturer Part Number: at45db021b
• Description: At45db021b 2-megabit 2.7-volt Only Dataflash
• Manufacturer: ATMEL Corporation

Figure 15-2. Algorithm for Randomly Modifying Data
Notes:
16. Sector Addressing
26
PA9
0
0
0
1
1. To preserve data integrity, each page of a DataFlash sector must be updated/rewritten at least once within every 10,000
2. A Page Address Pointer must be maintained to indicate which page is to be rewritten. The Auto Page Rewrite command
3. Other algorithms can be used to rewrite portions of the Flash array. Low power applications may choose to wait until 10,000
AT45DB021B
cumulative page erase/program operations.
must use the address specified by the Page Address Pointer.
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.
PA8
X
0
0
1
MAIN MEMORY PAGE PROGRAM
PA7
X
X
X
0
THROUGH BUFFER
(82H, 85H)
PA6
X
X
X
0
AUTO PAGE REWRITE
TO BUFFER TRANSFER
ADDRESS POINTER
MAIN MEMORY PAGE
INCREMENT PAGE
(53H, 55H)
(58H, 59H)
START
END
PA5
X
X
X
0
provide address of
page to modify
MEMORY PAGE PROGRAM
(2)
(2)
BUFFER TO MAIN
BUFFER WRITE
(84H, 87H)
(83H, 86H)
PA4
0
X
X
X
If planning to modify multiple
bytes currently stored within
a page of the Flash array
PA3
X
X
X
0
PA2 - PA0
X
X
X
X
1937J–DFLSH–9/05
Sector
0
1
2
3