X9118_09 Datasheet, PDF (3/17 Pages) Intersil Corporation – Single Digitally-Controlled (XDCP™) Potentiometer

X9118
Pin Configuration
X9118
(14 LD TSSOP)
TOP VIEW
V+
1
NC
2
A0
3
SCL
4
WP
5
SDA
6
V_SS
7
14
V_CC
13
R_L
12
R_H
11
R_W
10
NC
9
A1
8
V-
Pin Assignments
PIN
(TSSOP) SYMBOL
FUNCTION
1
V+ Analog Supply Voltage
2
NC No Connect
3
A0 Device Address for 2-wire bus
4
SCL Serial Clock for 2-wire bus
5
WP Hardware Write Protect
6
SDA Serial Data Input/Output for 2-wire bus
7
V_SS System Ground
8
V- Analog Supply Voltage
9
A1 Device Address for 2-wire bus
10
NC No Connect
11
R_W Wiper terminal of the Potentiometer
12
R_H High terminal of the Potentiometer
13
R_L Low terminal of the Potentiometer
14
V_CC System Supply Voltage
Pin Descriptions
Bus Interface Pins
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 a 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.
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.
SERIAL CLOCK (SCL)
This input is used by 2-wire master to supply 2-wire serial
clock to the X9118.
DEVICE ADDRESS (A1–A0)
The address inputs are used to set the least significant 2 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 X9118. A maximum
of 4 XDCP devices may occupy the 2-wire serial bus.
HARDWARE WRITE PROTECT INPUT (WP)
The WP pin when LOW prevents nonvolatile writes to the
Data Registers.
Potentiometer Pins
R_H, R_L
The R_H and R_L pins are equivalent to the terminal
connections on a mechanical potentiometer.
R_W
The wiper pin is equivalent to the wiper terminal of a
mechanical potentiometer.
Bias Supply Pins
SYSTEM SUPPLY VOLTAGE (V_CC) AND SUPPLY
GROUND (V_SS)
The V_CC pin is the system or digital supply voltage. The V_SS
pin is the system ground.
ANALOG SUPPLY VOLTAGES (V+ AND V-)
These supplies are the analog voltage supplies for the
potentiometer. The V+ supply is tied to the wiper switches
while the V- supply is used to bias the switches and the
internal P+ substrate of the integrated circuit. Both of these
supplies set the voltage limits of the potentiometer.
Other Pins
NO CONNECT
No connect pins should be left open. These pins are used for
Intersil manufacturing and testing purposes.
Principles of Operation
The X9118 is an integrated microcircuit incorporating a
resistor array and its registers and counters and the serial
interface logic providing direct communication between the
host and the digitally controlled potentiometer. This section
provides a detailed description of the following:
• Resistor Array Description
• Serial Interface Description
• Instruction and Register Description
Resistor Array Description
The X9118 is comprised of a resistor array. The array
contains 1023, in effect, discrete resistive segments that are
connected in series (see Figure 1). The physical ends of
each array are equivalent to the fixed terminals of a
mechanical potentiometer (R_H and R_L inputs).
3
FN8161.4
December 4, 2009