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32-Position Manual Up/Down Control
Potentiometer
Data Sheet
AD5228
Rev. B Document Feedback
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FEATURES
32-position digital potentiometer
10 kΩ, 50 kΩ, 100 kΩ end-to-end terminal resistance
Simple manual up/down control
Self-contained, requires only 2 pushbutton tactile switches
Built-in adaptive debouncer
Discrete step-up/step-down control
Autoscan up/down control with 4 steps per second
Pin-selectable zero-scale/midscale preset
Low potentiometer mode tempco, 5 ppm/°C
Low rheostat mode tempco, 35 ppm/°C
Digital control compatible
Ultralow power, I
DD
= 0.4 µA typ and 3 µA max
Low operating voltage, 2.7 V to 5.5 V
Temperature range, −40°C to +105°C
Compact thin SOT-23-8 (2.9 mm × 3 mm) Pb-free package
APPLICATIONS
Mechanical potentiometer and trimmer replacements
LCD backlight, contrast, and brightness controls
Digital volume control
Portable device-level adjustments
Electronic front panel-level controls
Programmable power supply
GENERAL DESCRIPTION
The AD5228 is Analog Devices’ latest 32-step-up/step-down
control digital potentiometer emulating mechanical potenti-
ometer operation
1
. Its simple up/down control interface allows
manual control with just two external pushbutton tactile
switches. The AD5228 is designed with a built-in adaptive
debouncer that ignores invalid bounces due to contact bounce
commonly found in mechanical switches. The debouncer is
adaptive, accommodating a variety of pushbutton tactile
switches that generally have less than 10 ms of bounce time
during contact closures. When choosing the switch, the user
should consult the timing specification of the switch to ensure
its suitability in an AD5228 application.
1
The terms digital potentiometer and RDAC are used interchangeably.
FUNCTIONAL BLOCK DIAGRAM
04422-0-001
UP/DOWN
CONTROL
LOGIC
DISCRETE
STEP/AUTO
SCAN DETECT
ADAPTIVE
DEBOUNCER
ZERO- OR MID-
SCALE PRESET
AD5228
PUSH-UP
BUTTON
PUSH-DOWN
BUTTON
R1 R2
D
E
C
O
D
E
A
W
B
V
DD
PRE GND
PU
PD
Figure 1.
The AD5228 can increment or decrement the resistance in
discrete steps or in autoscan mode. When the
PU
or
PD
button
is pressed briefly (no longer than 0.6 s), the resistance of the
AD5228 changes by one step. When the
PU
or
PD
button is
held continuously for more than a second, the device activates
the autoscan mode and changes four resistance steps per
second.
The AD5228 can also be controlled digitally; its up/down
features simplify microcontroller usage. The AD5228 is available
in a compact thin SOT-23-8 (TSOT-8) package. The part is
guaranteed to operate over the temperature range of −40°C to
+105°C.
The AD5228’s simple interface, small footprint, and very low
cost enable it to replace mechanical potentiometers and
trimmers with typically 3× improved resolution, solid-state
reliability, and faster adjustment, resulting in considerable cost
saving in end users’ systems.
Users who consider EEMEM potentiometers should refer to the
recommendations in the Applications section.
Table 1. Truth Table
PU
PD
Operation
1
0
0
R
WB
Decrement
0
1
R
WB
Increment
1
0
R
WB
Decrement
1 1 R
WB
Does Not Change
1
R
WA
increments if R
WB
decrements and vice versa.
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