CAT24C208

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Doc. No. 1044, Rev. F

© 2006 by Catalyst Semiconductor, Inc.

Characteristics subject to change without notice

(1) Data transfer may be initiated only when the bus is

not busy.

(2) During a data transfer, the data line must remain

stable whenever the clock line is high. Any changes

in the data line while the clock line is high will be

interpreted as a START or STOP condition.

START Condition

The START Condition precedes all commands to the

device, and is defined as a HIGH to LOW transition of

either SDA when the respective SCL is HIGH. The

CAT24C208 monitors the SDA and SCL lines and will

not respond until this condition is met.

STOP Condition

A LOW to HIGH transition of SDA when SCL is HIGH

determines the STOP condition. All operations must end

with a STOP condition.

Acknowledge

After a successful data transfer, each receiving device is

required to generate an acknowledge. The acknowledging

device pulls down the respective SDA line during the ninth

clock cycle, signaling that it received the 8 bits of data.

The CAT24C208 responds with an acknowledge after

receiving a START condition and its slave address. If the

device has been selected along with a write operation, it

responds with an acknowledge after receiving each 8-bit

byte.

When the CAT24C208 is in a READ mode it transmits 8

bits of data, releases the respective SDA line, and

monitors the line for an acknowledge. Once it receives

this acknowledge, the CAT24C208 will continue to

transmit data. If no acknowledge is sent by the Master,

the device terminates data transmission and waits for a

STOP condition.

After an unsuccessful data transfer an acknowledge will

not be issued (NACK) by the slave (CAT24C208), and

the master should abort the sequence. If continued the

device will read from or write to the wrong address in the

two instruction format with the segment pointers.

Figure 2. Acknowledge Timing

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9

START

SCL FROM

MASTER

BUS RELEASE DELAY (TRANSMITTER)

ACK DELAY

ACK SETUP

BUS RELEASE DELAY (RECEIVER)

DATA OUTPUT

FROM TRANSMITTER

DATA OUTPUT

FROM RECEIVER