CAT5128 Catalyst Semiconductor, CAT5128 Datasheet - Page 2

• Manufacturer Part Number: CAT5128
• Description: 32-tap Digital Up/down Control Potentiometer
• Manufacturer: Catalyst Semiconductor

CAT5128
PIN CONFIGURATION
PIN DESCRIPTION
UP
When DOWN
UP
toward the A terminal.
¯¯¯¯¯¯ : Step-Down Control Input
A high-to-low transition on DOWN
wiper to move one increment towards the B terminal.
A: High End Potentiometer Terminal
A is the high end terminal of the potentiometer. It is
not required that this terminal be connected to a
potential greater than the B terminal. Voltage applied
to the A terminal cannot exceed the supply voltage,
V
W: Wiper Potentiometer Terminal
W is the wiper terminal of the potentiometer. Its
position on the resistor array is controlled by the
control inputs, UP
W terminal cannot exceed the supply voltage, V
go below ground, GND.
B: Low End Potentiometer Terminal
B is the low end terminal of the potentiometer. It is not
required that this terminal be connected to a potential
less than the A terminal. Voltage applied to the B
terminal cannot exceed the supply voltage, V
below ground, GND. B and A are electrically
interchangeable.
Doc. No. MD-2128 Rev. B
DOWN
¯¯ : Step-Up Control Input
¯¯ input will cause the wiper to move one increment
CC
or go below ground, GND.
¯¯¯¯¯¯ input is high, a high-to-low transition on
¯¯¯¯¯¯ 2
DOWN
GND 4
UP
¯¯
SOT-23 8-Lead
A 3
1
¯¯ and DOWN
CAT
8
7
6
5
¯¯¯¯¯¯ .
V
NC
B
W
CC
¯¯¯¯¯¯ input will cause the
Voltage applied to the
CC
or go
CC
or
2
DEVICE OPERATION
The CAT5128 operates like a digitally controlled
potentiometer with A and B equivalent to the high and
low terminals and W equivalent to the mechanical
potentiometer's wiper. There are 32 available tap
positions including the resistor end points, A and B.
There are 31 resistor elements connected in series
between the A and B terminals. The wiper terminal is
connected to one of the 32 taps and controlled by two
inputs, UP
up/down counter whose output is decoded to select
the wiper position.
A
decrement one step the wiper position (R
decrease with 1LSB and R
If and only if DOWN
transition on UP
wiper position (R
will decrease with 1LSB).
The wiper, when at either fixed terminal, acts like its
mechanical equivalent and does not move beyond the
last position. When the CAT5128 is powered-down,
the wiper position is reset. When power is restored,
the counter is set to the mid point, tap 15.
PIN DESCRIPTIONS
¯¯¯¯¯¯ Step-Down Control
DOWN
Name Function
GND
V
UP
NC
¯¯
high-to-low
W
A
B
CC
¯¯ and DOWN
Step-Up Control
Potentiometer High Terminal
Ground
Wiper Terminal
Potentiometer Low Terminal
Not Connected
Supply Voltage
¯¯ input will increment one step the
¯¯¯¯¯¯ . These inputs control a five-bit
¯¯¯¯¯¯ input is high, a high-to-low
transition
WB
will increase with 1LSB and R
Characteristics subject to change without notice
WA
on
will increase with 1LSB).
© 2008 SCILLC. All rights reserved.
¯¯¯¯¯¯
DOWN
input
WB
will
will
WA