X9319 Datasheet, PDF (8/10 Pages) Xicor Inc. – Digitally Controlled Potentiometer (XDCP)

X9319
APPLICATIONS INFORMATION
Electronic digitally controlled (XDCP) potentiometers provide three powerful application advantages; (1) the vari-
ability and reliability of a solid-state potentiometer, (2) the flexibility of computer-based digital controls, and (3) the
retentivity of nonvolatile memory used for the storage of multiple potentiometer settings or data.
Basic Configurations of Electronic Potentiometers
V_REF
R_H
V_REF
R_W
R_L
Three terminal potentiometer;
variable voltage divider
I
Two terminal variable resistor;
variable current
Basic Circuits
Buffered Reference Voltage
R₁
+V
+5V
V_REF
R_W
+ ^LMC7101
–
V_OUT
V_OUT = V_W/R_W
Cascading Techniques
+V
+V
R_W
+V
(a)
X
R_W
(b)
Single Supply Inverting Amplifier
R₁ R₂
+8V
V_S
100K
+10V
–
+
100K
V_O
LMC7101
V_O = (R2/R1)V_S
Voltage Regulator
Offset Voltage Adjustment
V_IN
317
V_O (REG) _VS
R₁
R₂
R₁
100KΩ
+12V
–
I_adj
R₂
10KΩ
+
LMC7101
V_O (REG) = 1.25V (1+R₂/R₁)+I_adj R₂
10KΩ
+15V
10KΩ
REV 1.7 7/10/03
www.xicor.com
Comparator with Hysteresis
LT311A
V_S
–
+
V_O
V_O
R₁ R₂
V_UL = {R₁/(R₁+R₂)} V_O(max)
V_LL = {R₁/(R₁+R₂)} V_O(min)
(for additional circuits see AN115)
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