Datasheet

24LC21
DS21095K-page 8  1994-2012 Microchip Technology Inc.
It is required that VCLK be held at a logic high level in
order to program the device. This applies to byte write
and page write operation. Note that V
CLK can go low
while the device is in its self-timed program operation
and not affect programming.
FIGURE 4-1: BYTE WRITE
FIGURE 4-2: BYTE WRITE
Note: Page write operations are limited to writing
bytes within a single physical page,
regardless
of the number of bytes
actually being written. Physical page
boundaries start at addresses that are
integer multiples of the page buffer size (or
‘page size’) and end at addresses that are
integer multiples of [page size - 1]. If a
page Write command attempts to write
across a physical page boundary, the
result is that the data wraps around to the
beginning of the current page (overwriting
data previously stored there), instead of
being written to the next page as might be
expected. It is therefore necessary for the
application software to prevent page write
operations that would attempt to cross a
page boundary.
S P
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
S
T
A
R
T
S
T
O
P
Control
Byte
Word
Address
Data
A
C
K
A
C
K
A
C
K
VCLK
S P
BUS ACTIVITY
MASTER
SDA LINE
BUS ACTIVITY
S
T
A
R
T
S
T
O
P
Control
Byte
Word
Address
Data
A
C
K
A
C
K
A
C
K
VCLK
21095K.book Page 8 Wednesday, December 5, 2012 2:28 PM