X9313
computer-based digital controls, and (3) the retentivity of
nonvolatile memory used for the storage of multiple
potentiometer settings or data.
Applications Information
Electronic digitally controlled potentiometers (XDCP) provide
three powerful application advantages; (1) the variability and
reliability of a solid-state potentiometer, (2) the flexibility of
Basic Configurations of Electronic Potentiometers
V
R
V
R
V
H
L
V
/R
W
W
V
I
THREE-TERMINAL POTENTIOMETER;
VARIABLE VOLTAGE DIVIDER
TWO-TERMINAL VARIABLE RESISTOR;
VARIABLE CURRENT
Basic Circuits
BUFFERED REFERENCE VOLTAGE
CASCADING TECHNIQUES
+V
NONINVERTING AMPLIFIER
R
+V
+V
+5V
1
LM308A
V
+V
+
–
S
+5V
V
O
V
W
OP-07
+
–
V
X
REF
-5V
V
/R
W
V
W
OUT
R
2
-5V
R
1
V
W
V
= V /R
W W
OUT
(a)
(b)
V
= (1 + R / R )V
2 1 S
O
VOLTAGE REGULATOR
OFFSET VOLTAGE ADJUSTMENT
COMPARATOR WITH HYSTERESIS
R
R
2
1
LT311A
–
V
S
V
S
V
V
(REG)
V
O
317
IN
O
+
2
100kΩ
R
1
–
+
V
O
TL072
I
adj
R
R
1
10kΩ
10kΩ
R
2
10kΩ
V
V
= [R / (R + R )] V (max)
1 1 2 O
UL
LL
= [R / (R + R )] V (min)
1
1
2
O
V
(REG) = 1.25V (1 + R / R ) + I
R
ADJ 2
O
2
1
+12V
-12V
(for additional circuits see AN115)
FN8177.2
9
September 9, 2005
INTERSIL [ Intersil ]
