CAT5128
32‐tap Digital Up/Down
Control Potentiometer (POT)
Description
The CAT5128 is a single digital POT designed as an electronic
replacement for mechanical potentiometers and trim pots. Ideal for
automated adjustments on high volume production lines, they are also
well suited for applications where equipment requiring periodic
adjustment is either difficult to access or located in a hazardous or
remote environment.
The CAT5128 contains a 32-tap series resistor array connected
between two terminals A and B. An up/down counter and decoder that
are controlled by two input pins, determines which tap is connected to
the wiper, W. Wiper-control of the CAT5128 is accomplished with two
input control pins, UP and DOWN. A high-to-low transition on the UP
input increments the wiper position and a high-to-low transition on the
DOWN input decrements the wiper position. The tap position is not
stored in memory. The wiper is always set to the mid point, tap 15 at
power up.
The digital POT can be used as a three-terminal resistive divider or
as a two-terminal variable resistor. Digital potentiometers bring
variability and programmability to a wide variety of applications
including control, parameter adjustments, and signal processing.
Features
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SOT−23
TB SUFFIX
CASE 527AK
PIN CONFIGURATION
UP
DOWN
A
GND
(Top View)
1
V
CC
NC
B
W
32-position Linear Taper Potentiometer
Low Power CMOS Technology
Single Supply Operation: 2.5 V – 5.5 V
Discrete Step-up/Step-down Digital Control
Resistance Values: 10 kW, 50 kW and 100 kW
Available in SOT−23 8-lead Package
These Devices are Pb-Free, Halogen Free/BFR Free and are RoHS
Compliant
Automated Product Calibration
Remote Control Adjustments
Offset, Gain and Zero Control
Tamper-proof Calibrations
Contrast, Brightness and Volume Controls
Motor Controls and Feedback Systems
Programmable Analog Functions
MARKING DIAGRAM
AxYM
x
AH
AB
AC
Y
M
= H, B or C
= CAT5128TBI−00GT3
= CAT5128TBI−10GT3
= CAT5128TBI−50GT3
= Production Year (Last Digit)
= Production Month (1−9, O, N, D)
Applications
PIN DESCRIPTIONS
Pin Name
UP
DOWN
A
GND
W
B
NC
V
CC
Function
Step-Up Control
Step-Down Control
Potentiometer High Terminal
Ground
Wiper Terminal
Potentiometer Low Terminal
Not Connected
Supply Voltage
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 6 of this data sheet.
Semiconductor Components Industries, LLC, 2013
July, 2013
−
Rev. 4
1
Publication Order Number:
CAT5128/D
CAT5128
Functional Diagrams
V
CC
A
UP/DOWN
Control
DOWN
Power On
Recall
GND
5−BIT
UP/DOWN
COUNTER
ONE OF THIRTY TWO
DECODER
31
30
29
28
TRANS−
FER
GATES
RESISTOR
ARRAY
W
A
A
UP
W
V
CC
CONTROL
CIRCUITRY
B
UP
DOWN
GND
2
1
0
B
W
B
Figure 1. General
Figure 2. Detailed
Figure 3. Electronic
Potentiometer
Implementation
Pin Description
Device Operation
UP:
Step-Up Control Input
When DOWN input is high, a high-to-low transition on
UP input will cause the wiper to move one increment toward
the A terminal.
DOWN:
Step-Down Control Input
A high-to-low transition on DOWN input will cause the
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
CC
or go below ground, GND.
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
and DOWN. Voltage applied to the W terminal cannot
exceed the supply voltage, V
CC
or 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
CC
or go below ground, GND.
B and A are electrically interchangeable.
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 and DOWN. These
inputs control a five-bit up/down counter whose output is
decoded to select the wiper position.
A high-to-low transition on DOWN input will decrement
one step the wiper position (R
WB
will decrease with 1LSB
and R
WA
will increase with 1LSB). If and only if DOWN
input is high, a high-to-low transition on UP input will
increment one step the wiper position (R
WB
will increase
with 1LSB and R
WA
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.
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CAT5128
Table 1. OPERATION MODES
UP
High to Low
X
High
High to Low
Low
High
DOWN
High
Low
High to Low
High to Low
X
High
A
C
A
Operation
Wiper toward A – R
W
Increment
Wiper does not change
Wiper toward B – R
W
Decrement
Wiper toward B – R
W
Decrement
Wiper does not change
Wiper does not change
R
A
R
B
R
W
C
W
W
C
B
B
Figure 4. Potentiometer Equivalent Circuit
Table 2. ABSOLUTE MAXIMUM RATINGS
Parameters
Supply Voltage
V
CC
to GND
Inputs
UP to GND
DOWN to GND
A, B, W to GND
Operating Ambient Temperature
Industrial (‘I’ suffix)
Junction Temperature
Storage Temperature
Lead Soldering (10 seconds max)
Thermal Resistance
q
JA
Ratings
−0.5
to +7 V
−0.5
to V
CC
+0.5
−0.5
to V
CC
+0.5
−0.5
to V
CC
+0.5
−40
to +85
+150
−65
to 150
+300
230
Units
V
V
C
C
C
C
C/W
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
Table 3. DC ELECTRICAL CHARACTERISTICS
(V
CC
= +2.5 V to +5.5 V unless otherwise specified)
Symbol
POWER SUPPLY
V
CC
I
CC1
I
SB1
(Note 1)
Operating Voltage Range
Supply Current (Increment)
V
CC
= 5.5 V, f = 1 MHz, I
W
= 0
V
CC
= 5.5 V, f = 250 kHz, I
W
= 0
Supply Current (Standby)
UP, DOWN = V
CC
or GND
1. These parameters are periodically sampled and are not production tested.
2.5
–
–
–
–
–
–
0.01
5.5
100
50
1
V
mA
mA
mA
Parameter
Conditions
Min
Typ
Max
Units
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3
CAT5128
Table 4. LOGIC INPUTS
(V
CC
= +2.5 V to +5.5 V unless otherwise specified)
Symbol
I
IH
I
IL
V
IH1
V
IL1
V
IH2
V
IL2
Parameter
Input Leakage Current
Input Leakage Current
TTL High Level Input Voltage
TTL Low Level Input Voltage
CMOS High Level Input Voltage
CMOS Low Level Input Voltage
2.5 V
V
CC
5.5 V
Conditions
V
IN
= V
CC
V
IN
= 0 V
4.5 V
V
CC
5.5 V
Min
−
–
2
0
V
CC
x 0.7
−0.3
Typ
–
–
–
–
–
–
Max
10
−10
V
CC
0.8
V
CC
+ 0.3
V
CC
x 0.2
Units
mA
mA
V
V
V
V
Table 5. POTENTIOMETER CHARACTERISTICS
(V
CC
= +2.5 V to +5.5 V unless otherwise specified)
Symbol
R
POT
Parameter
Potentiometer Resistance
Conditions
−10
Device
−50
Device
−00
Device
Pot. Resistance Tolerance
V
A
V
B
INL
DNL
R
WI
I
W
TC
RPOT
TC
RATIO
V
N
(Note 4)
C
A
/C
B
/C
W
fc (Note 4)
2.
3.
4.
Voltage on A pin
Voltage on B pin
Resolution
Integral Linearity Error
Differential Linearity Error
Wiper Resistance
I
W
2
mA
I
W
2
mA
V
CC
= 5 V, I
W
= 1 mA
V
CC
= 2.5 V, I
W
= 1 mA
Wiper Current
TC of Pot Resistance
Ratiometric TC
Noise
Potentiometer Capacitances
Frequency Response
(Note 3)
(Note 4)
(Note 4)
100 kHz / 1 kHz
(Note 4)
Passive Attenuator, 10 kW
50
5
8/24
8/8/25
1.7
20
−0.5
−0.5
0
0
3.2
0.1
0.05
70
150
300
1
0.5
0.5
Min
Typ
(Note 2)
10
50
100
20
V
CC
V
CC
%
V
V
%
LSB
LSB
W
W
mA
ppm/C
ppm/C
nV/Hz
pF
MHz
Max
Units
kW
Typical values are for T
A
= 25C and nominal supply voltage.
I
W
= source or sink.
These parameters are periodically sampled and are not production tested.
Table 6. AC CONDITIONS OF TEST
V
CC
Range
Input Pulse Levels
Input Rise and Fall Times
Input Reference Levels
2.5 V
V
CC
5.5 V
0.2 V
CC
to 0.7 V
CC
10 ns
0.5 V
CC
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CAT5128
Table 7. AC OPERATING CHARACTERISTICS
(V
CC
= +2.5 V to +5.5 V, V
H
= V
CC
, V
L
= 0 V, unless othewise specified)
Symbol
t
UP
t
DOWN
t
UP_CYC
t
DOWN_CYC
t
UP_R,
t
UP_F
(Note 6)
t
DOWN_R,
t
DOWN_F
(Note 6)
t
UP_SET
t
DOWN_SET
t
PU
(Note 6)
Parameter
UP LOW Period
DOWN LOW Period
UP Cycle Time
DOWN Cycle Time
UP Rise and Fall Time
DOWN Rise and Fall Time
UP Settling Time
DOWN Settling Time
Power−up to Wiper Stable
Min
500
500
1
1
–
–
200
200
–
Typ
(Note 5)
–
–
–
–
–
–
–
–
–
Max
–
–
–
–
500
500
–
–
1
Units
ns
ns
ms
ms
ns
ns
ns
ns
ms
5. Typical values are for T
A
= 25C and nominal supply voltage.
6. This parameter is periodically sampled and not 100% tested.
Interface Timing Diagrams
t
UP_CYC
t
UP
UP
t
UP_R
90% 90%
10%
10%
MI (Note 7)
t
UP_SET
R
W
t
UP_F
Figure 5. Increment R
W
in Discrete Steps
t
DOWN_CYC
t
DOWN
DOWN
t
DOWN_R
90% 90%
10%
10%
t
DOWN_F
t
DOWN_SET
R
W
MI (Note 7)
Figure 6. Decrement R
W
in Discrete Steps
7. MI in the A.C. Timing diagram refers to the minimum incremental change in the W output due to a change in the wiper position.
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