A
PPLICATION
N
OTE
A V A I L A B L E
AN20 • AN42–53 • AN71 • AN73 • AN88 • AN91–92 • AN99 • AN115 • AN120 • AN124 • AN133 • AN134
Terminal Voltage ±5V, 64 Taps, 2-Wire
X9221
Dual Digitally Controlled Potentiometer (XDCP
™
)
FEATURES
• Two XDCPs in one package
• 2-wire serial interface
• Register oriented format
—Directly write wiper position
—Read wiper position
—Store as many as four positions per pot
• Instruction format
—Quick transfer of register contents to resistor
array
• Low power CMOS
• Direct write cell
—Endurance–100,000 writes per bit per register
—Register data retention–100 years
• Bytes of EEPROM memory
• Resistor array values
—2K
Ω
to 50K
Ω
mask programmable
• Resolution: 64 taps each pot
• 20-lead plastic DIP and 20-lead SOIC packages
DESCRIPTION
The X9221 integrates two digitally controlled potenti-
ometers (XDCP) on a monolithic CMOS integrated
microcircuit.
The digitally 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 2-wire
bus interface. Each potentiometer has associated with
it a volatile Wiper Counter Register (WCR) and 4 non-
volatile 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 through the switches. Power up recalls the con-
tents of DR0 to the WCR.
The XDCP can be used as a three-terminal potentiom-
eter or as a two-terminal variable resistor in a wide
variety of applications including control, parameter
adjustments, and signal processing.
BLOCK DIAGRAM
V
CC
V
SS
m
en
d
ed
ec
om
R0 R1
fo
r
Pot 0
Wiper
Counter
Register
(WCR)
V
H0
/R
H0
N
ew
Register
Array
Pot 1
R2 R3
R
SCL
SDA
A0
A1
A2
A3
ot
Interface
and
Control
Circuitry
Data
8
N
R0 R1
Wiper
Counter
Register
(WCR)
R2 R3
D
es
V
L0
/R
L0
V
W0
/R
W0
V
H1
/R
H1
V
L1
/R
L1
V
W1
/R
W1
ig
ns
REV 1.1 8/8/02
www.xicor.com
Characteristics subject to change without notice.
1 of 15
XICOR [ XICOR INC. ]
