
REV 1.1.6 8/1/02
Characteristics subject to change without notice.
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www.xicor.com
X9421
Single Digitally Controlled (XDCP) Potentiometer
FEATURES
Single Voltage Potentiometer
64 Resistor Taps
SPI Serial Interface for write, read, and transfer
operations of the potentiometer
Wiper Resistance, 150
4 Non-Volatile Data Registers
Non-Volatile Storage of Multiple Wiper Positions
Power On Recall. Loads Saved Wiper Position on
Power Up.
Standby Current < 5μA Max
V
CC
: 2.7V to 5.5V Operation
2.5K
, 10K
End to End Resistance
100 yr. Data Retention
Endurance: 100, 000 Data Changes per Bit per
Register
14-Lead TSSOP, 16-Lead SOIC
Low Power CMOS
Typical at 5V
DESCRIPTION
The X9421 integrates a single digitally controlled
potentiometer (XDCP) on a monolithic CMOS
integrated circuit.
The digital controlled potentiometer is implemented
using 63 resistive elements in a series array. Between
each element are tap points connected to the wiper
terminal through switches. The position of the wiper on
the array is controlled by the user through the SPI bus
interface. The potentiometer has associated with it a
volatile Wiper Counter Register (WCR) and a four non-
volatile Data Registers that can be directly written to
and read by the user. The contents of the WCR
controls the position of the wiper on the resistor array
though the switches. Powerup recalls the contents of
the default data register (DR0) to the WCR.
The XDCP can be used as a three-terminal
potentiometer or as a two terminal variable resistor in
a wide variety of applications including control,
parameter adjustments, and signal processing.
BLOCK DIAGRAM
64-taps
10K
inc / dec
R
H
/V
H
R
L
/V
L
R
W
/V
W
POT
V
CC
V
SS
SPI
bus
interface
address
data
status
write
trread
wiper
Power On Recall
Wiper Counter
Register (WCR)
Data Registers
4 Bytes
control
Bus
Interface &
Control
Low Noise/Low Power/SPI Bus
A
PPLICATION
N
OTES
A V A I L A B L E
AN99 AN115 AN120 AN124 AN133 AN134 AN135