CAT5110_07 Datasheet, PDF (6/16 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.
Figure 3. Positive LCD Bias Control
+5V
H
30V
W
CAT5110/CAT5125 L
V_OUT
Figure 4. Positive LCD Bias Control
+5V
H
30V
CAT5119/CAT5124 L
V_OUT
Figure 5a. Adjustable Gain Circuit
V_CC
V_IN
V_OUT
H
CAT5118/CAT5123 L
Figure 5b. Adjustable Gain Circuit
V_CC
V_IN
V_OUT
W
L
H
CAT5110/CAT5125
Doc. No. MD-2120, Rev. F

© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice