2

X24001

PIN DESCRIPTIONS

Serial Clock (SCL)

The SCL input is used to clock all data into and out of the

device.

Serial Data (SDA)

SDA is a bidirectional pin used to transfer data into and

out of the device. It is a push/pull output and does not

require the use of a pull-up resistor. During the program-

ming operation, SDA is an input.

PIN NAMES

Symbol

Description

NC

No Connect

Ground

Supply Voltage

SDA

Serial Data

SCL

Serial Clock

3830 PGM T01

DEVICE OPERATION

The X24001 supports a bidirectional bus oriented proto-

col. The protocol defines any device that sends data

onto the bus as a transmitter and the receiving device as

the receiver. The device controlling the transfer is a

master and the device being controlled is the slave. The

master will always initiate data transfers and provide the

clock for both transmit and receive operations. There-

fore, the X24001 will be considered a slave in all appli-

cations.

Clock and Data Conventions

Data states on the SDA line can change only during SCL

LOW. SDA state changes during SCL HIGH are re-

served for indicating start and stop conditions. Refer to

Figures 1 and 2.

Start Condition

All commands are preceded by the start condition,

which is a HIGH to LOW transition of SDA when SCL is

HIGH. The X24001 continuously monitors the SDA and

SCL lines for the start condition and will not respond to

any command until this condition has been met.

A start may be issued to terminate the input of a control

word or the input of data to be written. This will reset the

device and leave it ready to begin a new read or write

command. Because of the push/pull output, a start

cannot be generated while the part is outputting data.

Starts are also inhibited while a write is in progress.

Stop Condition

The stop condition is a LOW to HIGH transition of SDA

when SCL is HIGH. The stop condition is used to reset

the device during a command or data input sequence

and will leave the device in the standby mode. As with

starts, stops are inhibited when outputting data and

while a write is in progress.