CAT5110 Datasheet, PDF (6/15 Pages) Catalyst Semiconductor – 32-Tap MiniPot Digitally Programmable Potentiometers with 2-Wire Interface

CAT5110, CAT5118, CAT5119, CAT5123, CAT5124, CAT5125
APPLICATIONS INFORMATION
The MiniPots are intended for circuits requiring
digitally controlled adjustable resistance, such as LCD
contrast control, where voltage biasing adjusts the
display contrast.
Alternative Positive LCD Bias Control
An op amp can be used to provide buffering and gain
on the output of the CAT5110/CAT5125. This can be
done by connecting the wiper output to the positive
input of a noninverting op amp as shown in Figure 3.
Figure 4 shows a similar circuit for the CAT5119/
CAT5124.
Adjustable Gain
Figure 5 shows how to use either a variable resistor or
a potentiometer to digitally adjust the gain of a
noninverting op amp configuration, by connecting the
Minipot in series with a resistor to ground. The
MiniPots have a low 5ppm/ºC ratiometric tempco that
allows for a very stable adjustable gain configuration
over temperature.
+5V
H
W
CAT5110/CAT5125 L
30V
V_OUT
+5V
H
CAT5119/CAT5124 L
30V
V_OUT
Figure 3. Positive LCD Bias Control
V_CC
V_IN
V_OUT
H
CAT5118/CAT5123 L
Figure 5a. Adjustable Gain Circuit
Figure 4. Positive LCD Bias Control
V_CC
V_IN
V_OUT
W
L
H
CAT5110/CAT5125
Figure 5b. Adjustable Gain Circuit
Doc. No. MD-2120 Rev. K
6
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Characteristics subject to change without notice