AT45DB641E datasheet(39/78 Pages) RENESAS

39 / 78 page

DS-AT45DB641E-027 Rev. O

Page 39

6/30/23

AT45DB641E Datasheet

10.3 Auto Page Rewrite

This command only needs to be used if the possibility exists that static (non-changing) data are stored in a page

or pages of a sector and the other pages of the same sector are erased and programmed a large number of times.

Applications that modify data in a random fashion within a sector can fall into this category. To preserve data

integrity of a sector, each page within a sector must be updated/rewritten at least once within every 50,000

cumulative page erase/program operations within that sector. The Auto Page Rewrite command provides a simple

and efficient method to “refresh” a page in the main memory array in a single operation.

The Auto Page Rewrite command is a combination of the Main Memory Page to Buffer Transfer and Buffer to

Main Memory Page Program with Built-In Erase commands. With the Auto Page Rewrite command, a page of

data is first transferred from the main memory to Buffer 1 or Buffer 2 and then the same data (from Buffer 1 or

Buffer 2) are programmed back into the same page of main memory, essentially “refreshing” the contents of that

page. To start the Auto Page Rewrite operation with the standard DataFlash page size (264 bytes), a 1-byte

opcode, 58H for Buffer 1 or 59H for Buffer 2, must be clocked into the device followed by three address bytes

comprised of 15 page address bits (PA14-PA0) that specify the page in main memory to be rewritten, and 9

dummy bits.

To initiate an Auto Page Rewrite with the a binary page size (256 bytes), the opcode 58H for Buffer 1 or 59H for

Buffer 2, must be clocked into the device followed by three address bytes consisting of 1 dummy bit, 15 page

address bits (A22 - A8) that specify the page in the main memory that is to be rewritten, and 8 dummy bits. When

a low-to-high transition occurs on the CS pin, the part first transfers data from the page in main memory to a

buffer, and then programs the data from the buffer back into same page of main memory. The operation is

internally self-timed and takes place in a maximum time of tEP. During this time, the RDY/BUSY Status Register

indicates that the part is busy.

If a sector is programmed or reprogrammed sequentially page by page and the possibility does not exist that there

is a page or pages of static data, then the programming algorithm shown in Figure 51 is recommended.

Otherwise, if there is a chance that there is a page or pages of a sector that contains static data, then the

programming algorithm shown in Figure 52 is recommended. Contact Renesas Electronics for availability of

devices that are specified to exceed the 50,000 cycle cumulative limit.

Note: The Auto Page Rewrite command uses the same opcodes as the Read-Modify-Write command. If data

bytes are clocked into the device, then the device performs a Read-Modify-Write operation. See “Read-Modify-

Write” on page 19 for more details.

AT45DB641E Datasheet(PDF) 39 Page - Renesas Technology Corp