AT45DB021E datasheet(16/69 Pages) RENESAS

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DS-AT45DB021E-8789 Rev. N

Page 16

3/24/26

AT45DB021E Datasheet

When a low-to-high transition occurs on the CS pin, the device programs the data stored in the Buffer into the

specified page in the main memory. The page in main memory that is being programmed must have been

previously erased using one of the erase commands (Page Erase, Block Erase, Sector Erase, or Chip Erase).

The programming of the page is internally self-timed and must take place in a maximum time of tP. During this

time, the RDY/BUSY bit in the Status Register indicates that the device is busy.

The device also incorporates an intelligent programming algorithm that can detect when a byte location fails to

program properly. If a programming error arises, it is indicated by the EPE bit in the Status Register.

8.4

Main Memory Page Program through Buffer with Built-In Erase

The Main Memory Page Program through Buffer with Built-In Erase command combines the Buffer Write and

Buffer to Main Memory Page Program with Built-In Erase operations into a single operation to help simplify

application firmware development. With the Main Memory Page Program through Buffer with Built-In Erase

command, data is first clocked into the Buffer, the addressed page in memory is then automatically erased, and

then the contents of the Buffer are programmed into the just-erased main memory page.

To perform a Main Memory Page Program through Buffer using the standard DataFlash page size (264 bytes), an

opcode of 82h must first be clocked into the device followed by three address bytes comprised of five dummy bits,

10 page address bits (PA9 - PA0) that specify the page in the main memory to be written, and nine buffer address

bits (BFA8 - BFA0) that select the first byte in the Buffer to be written.

To perform a Main Memory Page Program through Buffer using the binary page size (256 bytes), an opcode of

82h must first be clocked into the device followed by three address bytes comprised of six dummy bits, 10 page

address bits (A17 - A8) that specify the page in the main memory to be written, and eight address bits (A7 - A0)

that selects the first byte in the Buffer to be written.

After all address bytes have been clocked in, the device takes data from the input pin (SI) and stores it in the

Buffer. If the end of the Buffer is reached, the device wraps around back to the beginning of the Buffer. When there

is a low-to-high transition on the CS pin, the device first erases the selected page in main memory (the erased

state is a Logic 1) and then program the data stored in the Buffer into that main memory page. Both the erasing

and the programming of the page are internally self-timed and must take place in a maximum time of tEP. During

this time, the RDY/BUSY bit in the Status Register indicates that the device is busy.

The device also incorporates intelligent erase and programming algorithms that can detect when a byte location

fails to erase or program properly. If an erase or program error arises, it is indicated by the EPE bit in the Status

8.5

Main Memory Byte/Page Program through Buffer without Built-In Erase

The Main Memory Byte/Page Program through the Buffer without Built-In Erase combines both the Buffer Write

and Buffer to Main Memory Program without Built-In Erase operations to allow any number of bytes (1 to 256/264

bytes) to be programmed directly into previously erased locations in the main memory array. With the Main

Memory Byte/Page Program through Buffer without Built-In Erase command, data is first clocked into Buffer, and

then only the bytes clocked into the Buffer are programmed into the pre-erased byte locations in main memory.

Multiple bytes up to the page size can be entered with one command sequence.

To perform a Main Memory Byte/Page Program through the Buffer using the standard DataFlash page size (264

bytes), an opcode of 02h must first be clocked into the device followed by three address bytes comprised of five

dummy bits, 10 page address bits (PA9 - PA0) that specify the page in the main memory to be written, and nine

buffer address bits (BFA8 - BFA0) that select the first byte in the Buffer to be written. After all address bytes are

clocked in, the device takes data from the input pin (SI) and stores it in the Buffer. Any number of bytes (1 to 264)

can be entered. If the end of the Buffer is reached, then the device wraps around back to the beginning of the

Buffer.

To perform a Main Memory Byte/Page Program through the Buffer using the binary page size (256 bytes), an

opcode of 02h must first be clocked into the device followed by three address bytes comprised of six dummy bits,

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