
32-Position Manual Up/Down Control
Potentiometer
AD5228
FEATURES
32-position digital potentiometer
10 k, 50 k, 100 k 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
Automotive 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
Rev.
0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.326.8703
2004 Analog Devices, Inc. All rights reserved.
www.analog.com
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
0
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 automotive 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
Table 1. Truth Table decrements and vice versa.