Rainbow Electronics MAX5499 - Manual (Page 17)

MAX5494–MAX5499
10-Bit, Dual, Nonvolatile, Linear-Taper
Digital Potentiometers
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Positive LCD Bias Control
Figures 12 and 13 show an application where the volt-
age-divider or variable resistor is used to make an
adjustable, positive LCD-bias voltage. The op amp pro-
vides buffering and gain to the resistor-divider network.
Programmable Filter
Figure 14 shows the configuration for a 1st-order pro-
grammable filter. The gain of the filter is adjusted by
R2, and the cutoff frequency is adjusted by R3. Use the
following equations to calculate the gain (G) and the
3dB cutoff frequency (f
C ).
Gain and Offset Voltage Adjustment
Figure 15 shows an application using the MAX5498/
MAX5499 to adjust the gain and nullify the offset voltage.
G
R
R
f
R C
C
= +
=
Ч Ч
1
1
2
1
2 3
π
V OUT
30V
5V
W_
H_
L_
1/2 MAX5494/MAX5495
1/2 MAX5498/MAX5499
MAX480
Figure 12. Positive LCD Bias Control Using a Voltage-Divider
V OUT
30V
5V
W_
L_
1/2 MAX5496–MAX5499
MAX480
Figure 13. Positive LCD Bias Control Using a Variable Resistor
V OUT
V IN
R1
R2
R3
C
W_
L_
W_
L_
1/2 MAX5496–MAX5499
1/2 MAX5496–MAX5499
Figure 14. Programmable Filter
V OUT
W_
L_
1/2 MAX5498/MAX5499
1/2 MAX5498/MAX5499
V
REF
W_
H_
L_
V IN
Figure 15. Gain- and Offset-Voltage Adjustment Circuit