MAX5160/MAX5161
Low-Power Digital Potentiometers
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Detailed Description
The MAX5160/MAX5161 consist of resistor arrays with
thirty-one resistive elements. Thirty-two tap points are
accessible to the wiper along the resistor string
between H and L. Logic inputs CS, U/D, and INC
determine the position of the wiper. With CS low and
U/D high, a high-to-low transition on INC increments the
internal counter, increasing the resistance between W
and L. When both CS and U/D are low, a high-to-low
INC transition decrements the internal counter, decreas-
ing the resistance between W and L. At either end
(maximum or minimum positions), additional transitions in
the direction of the end points will not change the counter
value (the counter will not wrap around).
The H and L terminals of the MAX5160 are similar to the
two end terminals of a mechanical potentiometer. The
tap W is equivalent to the variable tap (wiper) of the
potentiometer.
The MAX5161 is similar to the MAX5160 except that CS
internally connects to ground and the wiper terminal (W)
is shorted to the high terminal (H). The MAX5161 acts as
a variable resistor (a potentiometer with the wiper and
one end terminal shorted together).
The MAX5160/MAX5161 feature power-on reset circuit-
ry that sets the wiper position to midscale at power-up.
Applications Information
The MAX5160/MAX5161 are intended for circuits
requiring digitally controlled adjustable voltage or
adjustable gain, such as LCD contrast control, where
voltage biasing adjusts the display contrast.
Controlling a Switch-Mode
LCD Bias Generator
Figure 1 shows an application where the MAX5161 is
used with a MAX1771 to make an adjustable positive
LCD-bias circuit. The output of the MAX1771 is a posi-
tive voltage that is digitally controlled through the
MAX5160/MAX5161. Similarly, Figure 2 shows the
application of the MAX5161 in a digitally controlled
negative LCD-bias circuit along with the MAX774/
MAX775/MAX776.
