CAT5112 Datasheet, PDF (2/11 Pages) Catalyst Semiconductor – 32-Tap Digitally Programmable Potentiometer (DPP™)

CAT5112
PIN CONFIGURATION
PDIP 8-Lead (L)
SOIC 8 Lead (V)
MSOP 8 Lead (Z)
I¯N¯C¯ 1
8 V_CC
U/D¯ 2 _CAT 7 C¯¯S
R_H 3
6 R_L
GND 4
5 R_WB
TSSOP 8 Lead (Y)
C¯¯S 1
8 R_L
V_CC 2
7 R_WB
CAT
I¯N¯C¯ 3
6 GND
U/D¯ 4
5 R_H
PIN DESCRIPTION
I¯N¯C¯: Increment Control Input
The I¯N¯C¯ input (on the falling edge) 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 C¯¯S is low, any
high-to-low transition on I¯N¯C¯ will cause the wiper to
move one increment toward the R_H terminal. When in
a low state and C¯¯S is low, any high-to-low transition
on I¯N¯C¯ 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_WB: Wiper Potentiometer Terminal (Buffered)
R_WB is the buffered wiper terminal of the potentio–
meter. Its position on the resistor array is controlled by
the control inputs, I¯N¯C¯, U/D¯ and C¯¯S.
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.
C¯¯S: Chip Select
The chip select input is used to activate the control
input of the CAT5112 and is active low. When in a
PIN DESCRIPTIONS
Name Function
I¯N¯C¯ Increment Control
U/D¯ Up/Down Control
R_H Potentiometer High Terminal
GND Ground
R_WB Buffered Wiper Terminal
R_L Potentiometer Low Terminal
C¯¯S Chip Select
V_CC Supply Voltage
high state, activity on the I¯N¯C¯ and U/D¯ inputs will not
affect or change the position of the wiper.
DEVICE OPERATION
The CAT5112 operates like a digitally controlled
potentiometer with R_H and R_L equivalent to the high
and low terminals and R_WB equivalent to the mecha–
nical 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, I¯N¯C¯, U/D¯ and C¯¯S. These inputs control a
five-bit up/down counter whose output is decoded to
select the wiper position. The selected wiper position
can be stored in nonvolatile memory using the INC
and C¯¯S inputs.
With C¯¯S set LOW the CAT5112 is selected and will
respond to the U/D¯ and I¯N¯C¯ inputs. HIGH to LOW
transitions on I¯N¯C¯ wil 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. The value of the
counter is stored in nonvolatile memory whenever C¯¯S
transitions HIGH while the I¯N¯C¯ input is also HIGH.
When the CAT5112 is powered-down, the last stored
wiper counter position is maintained in the nonvolatile
memory. When power is restored, the contents of the
memory are recalled and the counter is set to the
value stored.
With I¯N¯C¯ set low, the CAT5112 may be deselected
and powered down without storing the current wiper
position in nonvolatile memory. This allows the system
to always power up to a preset value stored in non-
volatile memory.
Doc. No. MD-2002 Rev. O
2
© 2009 SCILLC. All rights reserved.
Characteristics subject to change without notice