X9279
PIN DESCRIPTIONS
Potentiometer Pins
R , R
Bus Interface Pins
H
L
The R and R pins are equivalent to the terminal
connections on a mechanical potentiometer.
H
L
SERIAL DATA INPUT/OUTPUT (SDA)
The SDA is a bidirectional serial data input/output pin
for a 2-Wire slave device and is used to transfer data
into and out of the device. It receives device address,
opcode, wiper register address and data sent from an
2-Wire master at the rising edge of the serial clock
SCL, and it shifts out data after each falling edge of the
serial clock SCL.
R
W
The wiper pin is equivalent to the wiper terminal of a
mechanical potentiometer.
Bias Supply Pins
SYSTEM SUPPLY VOLTAGE (V
) AND SUPPLY GROUND (V )
SS
It is an open drain output and may be wire-ORed with
any number of open drain or open collector outputs. An
open drain output requires the use of a pull-up resistor.
For selecting typical values, refer to the guidelines for
calculating typical values on the bus pull-up resistors
graph.
CC
The V pin is the system supply voltage. The V pin
CC
SS
is the system ground.
Other Pins
NO CONNECT
SERIAL CLOCK (SCL)
No connect pins should be left open. This pins are used
for Xicor manufacturing and testing purposes.
This input is used by 2-Wire master to supply 2-Wire
serial clock to the X9279.
HARDWARE WRITE PROTECT INPUT (WP)
DEVICE ADDRESS (A2 - A0)
The WP pin when LOW prevents nonvolatile writes to
the Data Registers.
The Address inputs are used to set the least significant
3 bits of the 8-bit slave address. A match in the slave
address serial data stream must be made with the
Address input in order to initiate communication with
the X9279. A maximum of 8 devices may occupy the 2-
Wire serial bus.
Characteristics subject to change without notice. 4 of 24
REV 1.1.7 2/6/03
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XICOR [ XICOR INC. ]
