CAT24C64
BUS RELEASE DELAY (TRANSMITTER)
BUS RELEASE DELAY (RECEIVER)
SCL FROM
MASTER
1
8
9
DATA OUTPUT
FROM TRANSMITTER
DATA OUTPUT
FROM RECEIVER
ACK SETUP (≥ t
)
SU:DAT
START
ACK DELAY (≤ t
)
AA
Figure 4. Acknowledge Timing
t
t
F
t
R
HIGH
t
t
LOW
LOW
SCL
t
t
HD:DAT
SU:STA
t
t
t
SU:DAT
SU:STO
HD:STA
SDA IN
t
BUF
t
AA
t
DH
SDA OUT
Figure 5. Bus Timing
WRITE OPERATIONS
Byte Write
Acknowledge Polling
To write data to memory, the Master creates a START
condition on the bus and then broadcasts a Slave address
with the R/W bit set to ‘0’. The Master then sends two
address bytes and a data byte and concludes the session by
creating a STOP condition on the bus. The Slave responds
with ACK after every byte sent by the Master (Figure 6). The
STOP starts the internal Write cycle, and while this
As soon (and as long) as internal Write is in progress, the
Slave will not acknowledge the Master. This feature enables
the Master to immediately follow-up with a new Read or
Write request, rather than wait for the maximum specified
Write time (t ) to elapse. Upon receiving a NoACK
WR
response from the Slave, the Master simply repeats the
request until the Slave responds with ACK.
operation is in progress (t ), the SDA output is tri-stated
and the Slave does not acknowledge the Master (Figure 7).
WR
Hardware Write Protection
With the WP pin held HIGH, the entire memory is
protected against Write operations. If the WP pin is left
floating or is grounded, it has no impact on the Write
operation. The state of the WP pin is strobed on the last
Page Write
The Byte Write operation can be expanded to Page Write,
by sending more than one data byte to the Slave before
issuing the STOP condition (Figure 8). Up to 32 (Note 10)
distinct data bytes can be loaded into the internal Page Write
Buffer starting at the address provided by the Master. The
page address is latched, and as long as the Master keeps
sending data, the internal byte address is incremented up to
the end of page, where it then wraps around (within the
page). New data can therefore replace data loaded earlier.
Following the STOP, data loaded during the Page Write
session will be written to memory in a single internal Write
st
falling edge of SCL immediately preceding the 1 data byte
(Figure 9). If the WP pin is HIGH during the strobe interval,
the Slave will not acknowledge the data byte and the Write
request will be rejected.
Delivery State
The CAT24C64 is shipped erased, i.e., all bytes are FFh.
10.CAT24C64 Rev. D (Not Recommended for New Designs)
has 64−Byte Page Write Buffer.
cycle (t ).
WR
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