CAT5115
Doc. No. MD-2117 Rev. J 2 © 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice
PIN CONFIGURATION
PDIP 8-Lead (L), SOIC 8-Lead (V),
MSOP 8-Lead (Z)
INC
¯¯¯
1
8
V
CC
U/D
¯
2
7
CS
¯¯
R
H
3
6
R
L
GND
4
5
R
WB
CAT
TSSOP 8-Lead (Y)
CS
¯¯
1
8
R
L
V
CC
2
7
R
WB
INC
¯¯¯
3
6
GND
U/D
¯
4
5
R
H
CAT
TDFN 8-Pad
(ZD7)
Top View
INC
¯¯¯
1
8
V
CC
U/D
¯
2
7
CS
¯¯
R
H
3
6
R
L
GND
4
5
R
WB
PIN DESCRIPTIONS
Name Function
INC
¯¯¯
Increment Control
U/D
¯
Up/Down Control
R
H
Potentiometer High Terminal
GND Ground
R
W
Buffered Wiper Terminal
R
L
Potentiometer Low Terminal
CS
¯¯
Chip Select
V
CC
Supply Voltage
PIN FUNCTION
INC
¯¯¯
: Increment Control Input
The INC
¯¯¯
input moves the wiper in the up or down
direction determined by the condition of the U/D
¯
input.
U/D
¯
: Up/Down Control Input
The U/D
¯
input controls the direction of the wiper
movement. When in a high state and CS
¯¯
is low, any
high-to-low transition on INC
¯¯¯
will cause the wiper to
move one increment toward the R
H
terminal. When in
a low state and CS
¯¯
is low, any high-to-low transition
on INC
¯¯¯
will cause the wiper to move one increment
towards the R
L
terminal.
R
H
: High End Potentiometer Terminal
R
H
is the high end terminal of the potentiometer. It is
not required that this terminal be connected to a
potential greater than the R
L
terminal. Voltage applied
to the R
H
terminal cannot exceed the supply voltage,
V
CC
or go below ground, GND.
R
W
: Wiper Potentiometer Terminal
R
W
is the wiper terminal of the potentiometer. Its
position on the resistor array is controlled by the
control inputs, INC
¯¯¯
, U/D
¯
and CS
¯¯
. Voltage applied to
the R
W
terminal cannot exceed the supply voltage,
V
CC
or go below ground, GND.
R
L
: Low End Potentiometer Terminal
R
L
is the low end terminal of the potentiometer. It is
not required that this terminal be connected to a
potential less than the R
H
terminal. Voltage applied to
the R
L
terminal cannot exceed the supply voltage, V
CC
or go below ground, GND. R
L
and R
H
are electrically
interchangeable.
CS
¯¯
: Chip Select
The chip select input is used to activate the control
input of the CAT5115 and is active low. When in a
high state, activity on the INC
¯¯¯
and U/D
¯
inputs will not
affect or change the position of the wiper.
DEVICE OPERATION
The CAT5115 operates like a digitally controlled
potentiometer with R
H
and R
L
equivalent to the high
and low terminals and R
W
equivalent to the
mechanical potentiometer's wiper. There are 32
available tap positions including the resistor end
points, R
H
and R
L
. There are 31 resistor elements
connected in series between the R
H
and R
L
terminals.
The wiper terminal is connected to one of the 32 taps
and controlled by three inputs, INC
¯¯¯
, U/D
¯
and CS
¯¯
.
These inputs control a five-bit up/down counter whose
output is decoded to select the wiper position.
With CS
¯¯
set LOW the CAT5115 is selected and will
respond to the U/D
¯
and INC
¯¯¯
inputs. HIGH to LOW
transitions on INC
¯¯¯
will increment or decrement the
wiper (depending on the state of the U/D
¯
input and
five-bit counter). The wiper, when at either fixed
terminal, acts like its mechanical equivalent and does
not move beyond the last position. When the
CAT5115 is powered-down, the wiper position is
reset. When power is restored, the counter is set to
the mid point, tap 15.
