MAX5527/MAX5528/MAX5529
One-Time Programmable, Linear-Taper Digital
Potentiometers
10 ______________________________________________________________________________________
Applications Information
Use the MAX5527/MAX5528/MAX5529 in applications
requiring digitally controlled adjustable resistance,
such as LCD contrast control where voltage biasing
adjusts the display contrast, or for programmable filters
with adjustable gain and/or cutoff frequency.
Positive LCD Bias Control
Figures 7 and 8 show an application where the voltage-
divider or variable resistor is used to make an adjustable,
positive LCD bias voltage. The op-amp provides buffer-
ing and gain to the resistor-divider network made by the
potentiometer (Figure 7), or to a fixed resistor and a
variable resistor (Figure 8).
Programmable Filter
Figure 9 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
), only up to frequencies one
decade below the wiper -3dB bandwidth.
Adjustable Voltage Reference
Figure 10 shows the MAX5527/MAX5528/MAX5529
used as the feedback resistors in an adjustable-voltage
reference application.
