X24001
PIN DESCRIPTIONS
Serial Clock (SCL)
Clock and Data Conventions
DatastatesontheSDAlinecanchangeonlyduringSCL
LOW. SDA state changes during SCL HIGH are re-
served for indicating start and stop conditions. Refer to
Figures 1 and 2.
The SCL input is used to clock all data into and out of the
device.
Serial Data (SDA)
Start Condition
SDA is a bidirectional pin used to transfer data into and
out of the device. It is a push/pull output and does not
requiretheuseofapull-upresistor. Duringtheprogram-
ming operation, SDA is an input.
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.
PIN NAMES
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.
Symbol
Description
No Connect
Ground
NC
V
SS
V
CC
Supply Voltage
Serial Data
Serial Clock
SDA
SCL
Stop Condition
3830 PGM T01
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.
DEVICE OPERATION
The X24001 supports a bidirectional bus oriented proto-
col. The protocol defines any device that sends data
ontothebusasatransmitterandthereceivingdeviceas
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.
2
XICOR [ XICOR INC. ]
