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Dual 64-
and
256-Position I
2
C Nonvolatile
Memory Digital Potentiometers
AD5251/AD5252
FEATURES
AD5251: Dual 64-position resolution
AD5252: Dual 256-position resolution
1 k, 10 k, 50 k, 100 k
1 stores wiper setting w/write protection
Power-on refreshed with EEMEM settings in 300 μs typ
EEMEM rewrite time = 540 μs typ
Resistance tolerance stored in nonvolatile memory
12 extra bytes in EEMEM for user-defined information
I
2
C compatible serial interface
Direct read/write access of RDAC
2
and EEMEM registers
Predefined linear increment/decrement commands
Predefined ±6 dB step change commands
Synchronous or aysynchronous dual channel update
Wiper setting read back
4 MHz bandwidth—1 k version
Single supply 2.7 V to 5.5 V
Dual supply ±2.25 V to ±2.75 V
2 slave address decoding bits allow operation of 4 devices
100-year typical data retention T
A
= 55°C
Operating temperature –40°C to +85°C
APPLICATIONS
Mechanical potentiometer replacement
General purpose DAC replacement
LCD panel V
COM
adjustment
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
White LED brightness adjustment
RF base station power amp bias control
Programmable gain and offset control
Programmable voltage-to-current conversion
Programmable power supply
Sensor calibrations
FUNDAMENTAL BLOCK DIAGRAM
RDAC1
REGIS-
TER
RDAC3
REGIS-
TER
RDAC1
RDAC3
DATA
CONTROL
COMMAND
DECODE LOGIC
ADDRESS
DECODE LOGIC
CONTROL LOGIC
AD5251/
AD5252
I
2
C
SERIAL
INTERFACE
POWER-
ON RESET
V
DD
V
SS
A1
W1
B1
A3
W3
B3
DGND
WP
SCL
SDA
AD0
AD1
RDAC EEMEM
RAB
TOL
0
EEMEM
POWER-ON
REFRESH
Figure 1.
1
The terms nonvolatile memory and EEMEM are used interchangeably.
2
The terms digital potentiometer and RDAC are used interchangeably.
The AD5251/AD5252 are dual-channel, I
2
C, nonvolatile mem-
ory, digitally controlled potentiometers with 64/256 positions,
respectively. These devices perform the same electronic adjust-
ment functions as mechanical potentiometers, trimmers, and
variable resistors. The parts’ versatile programmability allows
multiple modes of operation, including read/write access in the
RDAC and EEMEM registers, increment/decrement of
resistance, resistance changes in ±6 dB scales, wiper setting
readback, and extra EEMEM for storing user-defined infor-
mation such as memory data for other components, look-up
table, or system identification information.
The AD5251/AD5252 allow the host I
2
C controllers to write
any of the 64- or 256-step wiper settings in the RDAC registers
and store them in the EEMEM. Once the settings are stored,
they are restored automatically to the RDAC registers at system
power-on; the settings can also be restored dynamically.
The AD5251/AD5252 provide additional increment,
decrement, +6 dB step change, and –6 dB step change in
synchronous or asynchronous channel update modes. The
increment and decrement functions allow stepwise linear
adjustments, while ±6 dB step changes are equivalent to
doubling or halving the RDAC wiper setting. These functions
are useful for steep-slope nonlinear adjustments such as white
LED brightness and audio volume control. The parts have a
patented resistance tolerance storing function which enable the
user to access the EEMEM and obtain the absolute end-to-end
resistance values of the RDACs for precision applications.
The AD5251/AD5252 are available in TSSOP-14 packages in
1 k, 10 k, 50 k, and 100 k options and all parts can
operate over the –40°C to +85°C extended industrial
temperature range.