Rainbow Electronics AT45DB021D - Manual (Page 4)

4
3638K–DFLASH–11/2012
AT45DB021D
2. 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” illustrates 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 2-1. Memory Architecture Diagram
3. 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 13-1 through 13-7 . 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 nine 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 nine 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 eight 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 designate a page address and A7 - A0 denotes the eight 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
SECT
OR 0b
Page = 256/264-bytes
PAGE 0
PAGE 1
PAGE 6
PAGE 7
PAGE 8
PAGE 9
PAGE 1,022
PAGE 1,023
BLOCK 0
PAGE 14
PAGE 15
PAGE 16
PAGE 17
PAGE 18
BLOCK 1
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
SECT
OR 1
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