APPLICATION NOTE
A V A I L A B L E
AN99 • AN115 • AN120 • AN124 • AN133 • AN134 • AN135
Low Noise/Low Power/SPI Bus/256 Taps
X9250
Quad Digitally Controlled Potentiometers (XDCP™)
FEATURES
DESCRIPTION
• Four potentiometers in one package
• 256 resistor taps/pot–0.4% resolution
• SPI serial interface
The X9250 integrates
potentiometers (XDCP) on a monolithic CMOS
integrated circuit.
4
digitally controlled
• Wiper resistance, 40Ω typical @ V
= 5V
CC
The digitally controlled potentiometer is implemented
using 255 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. Each potentiometer has
associated with it a volatile Wiper Counter Register
(WCR) and 4 nonvolatile Data Registers (DR0:DR3)
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. Power
up recalls the contents of DR0 to the WCR.
• Four nonvolatile data registers for each pot
• Nonvolatile storage of wiper position
• Standby current < 5µA max (total package)
• Power supplies
—V
= 2.7V to 5.5V
CC
—V+ = 2.7V to 5.5V
—V– = -2.7V to -5.5V
• 100KΩ, 50KΩ total pot resistance
• High reliability
—Endurance – 100,000 data changes per bit per
register
—Register data retention – 100 years
• 24-lead SOIC, 24-lead TSSOP, 24-lead CSP (Chip
Scale Package)
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.
• Dual supply version of X9251
BLOCK DIAGRAM
V
V+
V-
CC
Pot 0
V
SS
R
R
R
R
V /R
H0 H0
R
R
R
R
0
2
1
3
0
2
1
3
Wiper
V
/R
Wiper
Counter
Register
(WCR)
H2 H2
Resistor
Array
Pot 2
Counter
Register
(WCR)
V
/R
L0 L0
HOLD
V
/R
L2 L2
CS
SCK
SO
V
V
/R
W0 W0
V
/R
W2 W2
Interface
and
Control
SI
8
Circuitry
A0
A1
/R
W1 W1
Data
V
V
/R
W3 W3
WP
R
R
R
R
0
2
1
3
R
R
R
R
V
/R
Wiper
Counter
Register
(WCR)
0
2
1
3
H1 H1
/R
Wiper
Counter
Register
(WCR)
H3 H3
Resistor
Array
Pot1
Resistor
Array
Pot 3
V
/R
L1 L1
V
/R
L3 H3
Characteristics subject to change without notice. 1 of 21
REV 1.1.5 1/31/03
www.xicor.com
XICOR [ XICOR INC. ]
