MAX5160 Maxim, MAX5160 Datasheet - Page 5

• Manufacturer Part Number: MAX5160
• Description: Low-Power Digital Potentiometers
• Manufacturer: Maxim

The MAX5160/MAX5161 consist of resistor arrays with
31 resistive elements. Thirty-two tap points are accessi-
ble to the wiper along the resistor string between H and
L. Logic inputs CS, U/D, and INC determine the posi-
tion 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, decreasing the resis-
tance between W and L. At either end (maximum or mini-
mum 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
Figure 1. Adjustable Positive LCD Bias
0.1 F
V
68 F
V
REF
IN
C3
C1
= 5V
= 1.5V
5
4
6
REF
SHDN
AGND
C2
0.1 F
MAX1771
GND
V+
_______________________________________________________________________________________
2
7
Detailed Description
EXT
CS
FB
MAX5161
1
8
3
V
V
22 H
OUT(MAX)
OUT(MIN)
V
V
REF
REF
L1
MTD20N03HDL
N
Low-Power Digital Potentiometers
1N5817-22
R
40m
R1
SENSE
=
=
R1
R2
(
D1
R1 + R
+ 1
R
300 F
VAR
VAR(MAX)
R2
C4
C5
R2
V
)
OUT
AT 0.5A
+ 1
= 12V
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.
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.
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.
Figure 2. Adjustable Negative LCD Bias
150 F
V
IN
C1
V
V
R1 + R
OUT(MAX)
REF
V
REF
MAX5161
- V
VAR
FB
C2
0.1 F
=
5 A (FOR 2% GAIN-SETTING ACCURACY)
R2
R1
R2
R1
,
Applications Information
V
OUT(MIN)
C3
0.1 F
R
V
VAR
REF
1
3
2
4
Controlling a Switch-Mode
OUT
SHDN
FB
REF
=
R1 + R
MAX774
MAX775
MAX776
R2
GND
VAR
8
LCD Bias Generator
*
MAX775, MAX776 = 120 F, 20V
MAX774 = 330 F, 10V
EXT
CS
V+
5
6
7
22 H
L1
P
Q1
Si9435
R3
0.07
1N5822/
MBR340
C4
*
V
OUT
5