A
PPLICATION
N
OTE
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
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•
•
•
•
•
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•
Four potentiometers in one package
256 resistor taps/pot–0.4% resolution
SPI serial interface
Wiper resistance, 40
Ω
typical @ V
CC
= 5V
Four nonvolatile data registers for each pot
Nonvolatile storage of wiper position
Standby current < 5µA max (total package)
Power supplies
—V
CC
= 2.7V to 5.5V
—V+ = 2.7V to 5.5V
—V– = -2.7V to -5.5V
100K
Ω
, 50K
Ω
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)
Dual supply version of X9251
DESCRIPTION
The X9250 integrates 4 digitally controlled
potentiometers (XDCP) on a monolithic CMOS
integrated circuit.
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.
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.
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BLOCK DIAGRAM
V
CC
V
SS
V+
V-
R
0
R
1
Wiper
Counter
Register
(WCR)
Pot 0
V
H0
/R
H0
R
0
R
1
Wiper
Counter
Register
(WCR)
V
H2
/R
H2
HOLD
CS
SCK
SO
SI
A0
A1
WP
R
2
R
3
V
L0
/R
L0
V
W0
/R
W0
R
2
R
3
Resistor
Array
Pot 2
V
L2
/R
L2
V
W2
/R
W2
Interface
and
Control
Circuitry
Data
8
V
W1
/R
W1
R
0
R
1
Wiper
Counter
Register
(WCR)
V
H1
/R
H1
R
0
R
1
Wiper
Counter
Register
(WCR)
V
W3
/R
W3
V
H3
/R
H3
R
2
R
3
Resistor
Array
Pot1
V
L1
/R
L1
R
2
R
3
Resistor
Array
Pot 3
V
L3
/R
H3
REV 1.1.5 1/31/03
www.xicor.com
Characteristics subject to change without notice.
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XICOR [ XICOR INC. ]
