User Manual

20
AT45DB642
1638F–DFLSH–09/02
Read Operations
The following block diagram and waveforms illustrate the various read sequences available.
Main Memory Page Read
Main Memory Page to Buffer Transfer (Data from Flash Page Read into Buffer)
Buffer Read
FLASH MEMORY ARRAY
PAGE (1056 BYTES)
BUFFER 2 (1056 BYTES)BUFFER 1 (1056 BYTES)
I/O INTERFACE
MAIN MEMORY
PAGE TO
BUFFER 1
MAIN MEMORY
PAGE TO
BUFFER 2
MAIN MEMORY
PAGE READ
BUFFER 1
READ
BUFFER 2
READ
SO
I/O7 - I/O0
SI or I/O7 - I/O0
(INPUT)
CMD
PA12-5
PA4-0, BA10-8
BA7-0 X
X
CS
nn+1
SO or I/O7 - I/O0
(OUTPUT)
SI or I/O7 - I/O0
(INPUT)
CMD
PA12-5 PA4-0, XXX X
Starts reading page data into buffer
CS
SO or I/O7 - I/O0
(OUTPUT)
SI or I/O7 - I/O0
(INPUT)
CMD
X
BFA10-8
BFA7-0
CS
n n+1 SO or I/O7 - I/O0
(OUTPUT)
X
Each transition
represents 8 bits
n=1stbyteread
n+1 = 2nd byte read