CAT5123_13 Datasheet, PDF (6/11 Pages) ON Semiconductor – 32‐tap Digital Potentiometers (POTs)

CAT5110, CAT5118, CAT5119, CAT5123, CAT5124, CAT5125
APPLICATIONS INFORMATION
The devices 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 9. Figure 10 shows
a similar circuit for the CAT5119/CAT5124.
Adjustable Gain
Figures 11 and 12 show how to use either a variable
resistor or a potentiometer to digitally adjust the gain of a
noninverting op amp configuration, by connecting the
devices in series with a resistor to ground. The devices have
a low 5 ppm/C ratiometric tempco that allows for a very
stable adjustable gain configuration over temperature.
+5 V
H
30 V
+5 V
H
30 V
W
CAT5110/CAT5125 L
V_OUT
CAT5119/CAT5124 ^L
V_OUT
Figure 9. Positive LCD Bias Control
V_CC
V_IN
V_OUT
H
CAT5118/CAT5123 ^L
Figure 11. Adjustable Gain Circuit
Figure 10. Positive LCD Bias Control
V_CC
V_IN
V_OUT
LW
H
CAT5110/CAT5125
Figure 12. Adjustable Gain Circuit
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