at45db021d-ssh-sl955 ATMEL Corporation, at45db021d-ssh-sl955 Datasheet - Page 4

• Manufacturer Part Number: at45db021d-ssh-sl955
• Description: 2-megabit 2.7-volt Minimum Dataflash
• Manufacturer: ATMEL Corporation

4. Memory Array
Figure 4-1.
5. Device Operation
4
SECTOR ARCHITECTURE
AT45DB021D
SECTOR 1 = 128 Pages
SECTOR 6 = 128 Pages
SECTOR 0b = 120 Pages
SECTOR 7 = 128 Pages
SECTOR 0a = 8 Pages
32,768/33,792 bytes
32,768/33,792
32,768/33,792
31,744/32,726 bytes
2,048/2,112 bytes
Memory Architecture Diagram
bytes
bytes
To provide optimal flexibility, the memory array of the AT45DB021D is divided into three levels of
granularity comprising of sectors, blocks, and pages. The “Memory Architecture Diagram” illus-
trates the breakdown of each level and details the number of pages per sector and block. All
program operations to the DataFlash occur on a page-by-page basis. The erase operations can
be performed at the chip, sector, block or page level.
The device operation is controlled by instructions from the host processor. The list of instructions
and their associated opcodes are contained in
starts with the falling edge of CS followed by the appropriate 8-bit opcode and the desired buffer
or main memory address location. While the CS pin is low, toggling the SCK pin controls the
loading of the opcode and the desired buffer or main memory address location through the SI
(serial input) pin. All instructions, addresses, and data are transferred with the most significant
bit (MSB) first.
Buffer addressing for the DataFlash standard page size (264 bytes) is referenced in the
datasheet using the terminology BFA8 - BFA0 to denote the 9 address bits required to designate
a byte address within a buffer. Main memory addressing is referenced using the terminology
PA9 - PA0 and BA8 - BA0, where PA9 - PA0 denotes the 10 address bits required to designate
a page address and BA8 - BA0 denotes the 9 address bits required to designate a byte address
within the page.
For the “Power of 2” binary page size (256 bytes), the Buffer addressing is referenced in the
datasheet using the conventional terminology BFA7 - BFA0 to denote the 8 address bits
required to designate a byte address within a buffer. Main memory addressing is referenced
using the terminology A17 - A0, where A17 - A8 denotes the 10 address bits required to desig-
nate a page address and A7 - A0 denotes the 8 address bits required to designate a byte
address within a page.
SECTOR 0a
BLOCK ARCHITECTURE
Block = 1,024/1,056 bytes
BLOCK 126
BLOCK 127
BLOCK 14
BLOCK 15
BLOCK 16
BLOCK 17
BLOCK 30
BLOCK 31
BLOCK 32
BLOCK 33
BLOCK 0
BLOCK 1
BLOCK 2
Tables 15-1 through
8 Pages
PAGE ARCHITECTURE
15-7. A valid instruction
Page = 256/264 bytes
PAGE 1,022
PAGE 1,023
PAGE 14
PAGE 15
PAGE 16
PAGE 17
PAGE 18
PAGE 0
PAGE 1
PAGE 6
PAGE 7
PAGE 8
PAGE 9
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