User Manual

9
AT45DB642
1638F–DFLSH–09/02
MAIN MEMORY PAGE TO BUFFER COMPARE: A page of data in main memory can be
compared to the data in buffer 1 or buffer 2. To initiate the operation, a 1-byte opcode, 60H for
buffer 1 and 61H for buffer 2, must be clocked into the device, followed by three address bytes
consisting of 13 page address bits (PA12 - PA0) that specify the page in the main memory that
is to be compared to the buffer, and 11 don’tcarebits.TheCS
pin must be low while toggling
the SCK/CLK pin to load the opcode and the address bytes from the input pins (SI or I/O7 -
I/O0). On the low-to-high transition of the CS
pin, the 1056 bytes in the selected main memory
page will be compared with the 1056 bytes in buffer 1 or buffer 2. During this time (t
XFR
), the
status register and the RDY/BUSY
pin will indicate that the part is busy. On completion of the
compare operation, bit 6 of the status register is updated with the result of the compare.
AUTO PAGE REWRITE: This mode is only needed if multiple bytes within a page or multiple
pages of data are modified in a random fashion. This mode is a combination of two operations:
Main Memory Page to Buffer Transfer and Buffer to Main Memory Page Program with Built-in
Erase. 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) is programmed back into its original page of
main memory. To start the rewrite operation, 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 13
page address bits (PA12 - PA0) that specify the page in main memory to be rewritten and 11
don’t care bits. When a low-to-high transition occurs on the CS
pin, the part will first transfer
data from the page in main memory to a buffer and then program the data from the buffer back
into same page of main memory. The operation is internally self-timed and should take place
in a maximum time of t
EP
. During this time, the status register and the RDY/BUSY pin will indi-
cate that the part is busy.
If a sector is programmed or reprogrammed sequentially page by page, then the programming
algorithm shown in Figure 1 (page 33) is recommended. Otherwise, if multiple bytes in a page
or several pages are programmed randomly in a sector, then the programming algorithm
shown in Figure 2 (page 34) is recommended. Each page within a sector must be
updated/rewritten at least once within every 10,000 cumulative page erase/program opera-
tions in that sector.
Operation Mode
Summary
The modes described can be separated into two groups – modes that make use of the Flash
memory array (Group A) and modes that do not make use of the Flash memory array
(Group B).
Group A modes consist of:
1. Main Memory Page to Buffer 1 (or 2) Transfer
2. Main Memory Page to Buffer 1 (or 2) Compare
3. Buffer 1 (or 2) to Main Memory Page Program with Built-in Erase
4. Buffer 1 (or 2) to Main Memory Page Program without Built-in Erase
5. Page Erase
6. Block Erase
7. Main Memory Page Program through Buffer
8. Auto Page Rewrite
9. Group B modes consist of:
10. Buffer 1 (or 2) Read
11. Buffer 1 (or 2) Write
12. Status Register Read
If a Group A mode is in progress (not fully completed), then another mode in Group A should
not be started. However, during this time in which a Group A mode is in progress, modes in
Group B can be started.