3-Channel Digital Potentiometer with
Nonvolatile Memory

AD5255


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 www.analog.com
Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
FEATURES
3 channels:
Dual 512-position
Single 128-position
25 kΩ or 250 kΩ full-scale resistance
Low temperature coefficient:
Potentiometer divider 15 ppm/°C
Rheostat mode 35 ppm/°C
Nonvolatile memory retains wiper settings
Permanent memory write protection
Linear increment/decrement
±6 dB increment/decrement
I
2
C-compatible serial interface
2.7 V to 5.5 V single-supply operation
±2.25 V to ±2.75 V dual-supply operation
Power-on reset time
256 bytes general-purpose user EEPROM
11 bytes RDAC user EEPROM
GBIC and SFP compliant EEPROM
100-year typical data retention at TA = 55°C
APPLICATIONS
Mechanical potentiometer replacement
RGB LED backlight control
White LED brightness adjustment
Programmable gain and offset control
Programmable filters
FUNCTIONAL BLOCK DIAGRAM
A0
W0
B0
A1
W1
B1
A2
W2
B2
RDAC0
RDAC0
REGIST
ER
RDAC1
REGIST
ER
RDAC2
REGIST
ER
9 BIT
RDAC1
9 BIT
RDAC2
7 BIT
DATA
CONTROL
COMMAND
DECODE
LOGIC
ADDRESS
DECODE
LOGIC
DECODE
LOGIC
POWER-ON
RESET
I
2
C
SERIAL
INTERFACE
32 BYTES
RDAC
EEPROM
256 BYTES
USER
EEPROM
V
DD
V
SS
GND
SCL
SDA
A0_RDAC
A1_RDAC
A0_E
A1_E
RS
WP
04555-0-001
Figure 1.


GENERAL DESCRIPTION
The AD5255 provides dual 512-position and a single
128-position digitally controlled variable resistors
1
(VR) in a
TSSOP package. This device performs the same electronic
adjustment function as a potentiometer, trimmer, or variable
resistor. Each VR offers a completely programmable value of
resistance between the A terminal and the wiper or the B
terminal and the wiper. The fixed A-to-B terminal resistance of
25 kΩ or 250 kΩ has a 1% channel-to-channel matching
tolerance and a nominal temperature coefficient of 35 ppm/°C.
Wiper position programming, EEPROM
2
reading, and EEPROM
writing is conducted via the standard 2-wire I
2
C interface. Pre-
vious/default wiper position settings can be stored in memory,
and refreshed upon system power-up.
Additional features of the AD5255 include preprogrammed
linear and logarithmic increment/decrement wiper changing.
The actual resistor tolerances are stored in EEPROM so that the
actual end-to-end resistance is known, which is valuable for
calibration in precision applications.
The AD5255 is available in a 24-lead TSSOP package. All parts
are guaranteed to operate over the extended industrial tempera-
ture range of −40°C to +85°C.

1
The terms programmable resistor, variable resistor, RDAC, and digital
potentiometer are used interchangeably.
2
The terms nonvolatile memory, EEMEM, and EEPROM are used
interchangeably.