AT45DB021D_09 datasheet(4/54 Pages) ATMEL

4 / 54 page

3638I–DFLASH–04/09

AT45DB021D

4. Memory Array

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.

Figure 4-1.

Memory Architecture Diagram

5. Device Operation

The device operation is controlled by instructions from the host processor. The list of instructions

and their associated opcodes are contained in Tables 15-1 through 15-7. A valid instruction

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 = 8 Pages

2,048/2,112 bytes

SECTOR 0b = 120 Pages

31,744/32,726 bytes

Block = 1,024/1,056 bytes

8 Pages

SECTOR 0a

Page = 256/264 bytes

PAGE 0

PAGE 1

PAGE 6

PAGE 7

PAGE 8

PAGE 9

PAGE 1,022

PAGE 1,023

PAGE 14

PAGE 15

PAGE 16

PAGE 17

PAGE 18

SECTOR ARCHITECTURE

BLOCK ARCHITECTURE

PAGE ARCHITECTURE

BLOCK 0

BLOCK 1

BLOCK 14

BLOCK 15

BLOCK 16

BLOCK 17

BLOCK 126

BLOCK 127

BLOCK 30

BLOCK 31

BLOCK 32

BLOCK 33

SECTOR 7 = 128 Pages

32,768/33,792 bytes

BLOCK 2

SECTOR 1 = 128 Pages

32,768/33,792 bytes

SECTOR 6 = 128 Pages

32,768/33,792 bytes

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