6

AT45DB021B

1937F–DFLSH–10/02

place in a maximum time of t

part is busy.

BUFFER TO MAIN MEMORY PAGE PROGRAM WITHOUT BUILT-IN ERASE: Aprevi-

ously erased page within main memory can be programmed with the contents of either

buffer 1 or buffer 2. To start the operation, an 8-bit opcode (88H for buffer 1 or 89H for

buffer 2) must be followed by the five reserved bits, 10 address bits (PA9 - PA0) that

specify the page in the main memory to be written, and nine additional don’tcare bits.

When a low-to-high transition occurs on the CS pin, the part will program the data stored

in the buffer into the specified page in the main memory. It is necessary that the page in

main memory that is being programmed has been previously erased. The programming

of the page is internally self-timed and should take place in a maximum time of t

ing this time, the status register will indicate that the part is busy.

Successive page programming operations without doing a page erase are not recom-

mended. In other words, changing bytes within a page from a “1” to a “0” during multiple

page programming operations without erasing that page is not recommended.

PAGE ERASE: The optional Page Erase command can be used to individually erase

any page in the main memory array allowing the Buffer to Main Memory Page Program

without Built-in Erase command to be utilized at a later time. To perform a Page Erase,

an opcode of 81H must be loaded into the device, followed by five reserved bits, ten

address bits (PA9-PA0), and nine don’t care bits. The ten address bits are used to spec-

ify which page of the memory array is to be erased. When a low-to-high transition occurs

on the CS pin, the part will erase the selected page to 1s. The erase operation is inter-

nally self-timed and should take place in a maximum time of t

status register will indicate that the part is busy.

BLOCK ERASE: A block of eight pages can be erased at one time allowing the Buffer

to Main Memory Page Program without Built-in Erase command to be utilized to reduce

programming times when writing large amounts of data to the device. To perform a

Block Erase, an opcode of 50H must be loaded into the device, followed by five

reserved bits, seven address bits (PA9 -PA3), and 12 don’t care bits. The seven address

bits are used to specify which block of eight pages is to be erased. When a low-to-high

transition occurs on the CS pin, the part will erase the selected block of eight pages to

1s. The erase operation is internally self-timed and should take place in a maximum

time of t

Block Erase Addressing

PA9

PA8

PA7

PA6

PA5

PA4

PA3

PA2

PA1

PA0

Block

0000000

X

X

X

0

0000001

X

X

X

1

0000010

X

X

X

2

0000011

X

X

X

3

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

1111100

X

X

X

124

1111101

X

X

X

125

1111110

X

X

X

126

1111111

X

X

X

127