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Dual 64-and 256-Position I2C Nonvolatile
Memory Digital Potentiometers
AD5251/AD5252
FEATURES
AD5251: Dual 64-position resolution
AD5252: Dual 256-position resolution
1 kΩ, 10 kΩ, 50 kΩ, 100 kΩ
Nonvolatile memory1 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
I2C compatible serial interface
Direct read/write access of RDAC2 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 kΩ 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 TA = 55°C
Operating temperature –40°C to +85°C
APPLICATIONS
Mechanical potentiometer replacement
General purpose DAC replacement
LCD panel VCOM adjustment
GENERAL DESCRIPTION
The AD5251/AD5252 are dual-channel, I2C, 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 I2C 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,
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.
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
VDD
VSS
DGND
WP
SCL
SDA
AD0
AD1
I2C
SERIAL
INTERFACE
POWER-
ON RESET
RDAC EEMEM
EEMEM
POWER-ON
REFRESH
RAB
TOL
RDAC1
REGIS-
TER
RDAC1
DATA
CONTROL
RDAC3
REGIS-
TER
RDAC3
COMMAND
DECODE LOGIC
ADDRESS
DECODE LOGIC
CONTROL LOGIC
AD5251/
AD5252
A1
W1
B1
A3
W3
B3
Figure 1.
1The terms nonvolatile memory and EEMEM are used interchangeably.
2The terms digital potentiometer and RDAC are used interchangeably.
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 kΩ, 10 kΩ, 50 kΩ, and 100 kΩ options and all parts can
operate over the –40°C to +85°C extended industrial
temperature range.
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.

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AD5251/AD5252
TABLE OF CONTENTS
Electrical Characteristics ................................................................. 3
Interface Timing Characteristics................................................ 7
Absolute Maximum Ratings............................................................ 8
ESD Caution.................................................................................. 8
Pin Configuration and Function Description .............................. 9
I2C Interface Timing Diagram.................................................... 9
I2C Interface General Description................................................ 10
I2C Interface Detail Description ................................................... 11
RDAC/EEMEM Write ............................................................... 11
I2C Compatible 2-Wire Serial Bus................................................ 15
Typical Performance Characteristics ........................................... 16
Operational Overview.................................................................... 20
Linear Increment and Decrement Commands ...................... 20
±6 dB Adjustments (Doubling/Halving WIPER Setting) ..... 20
REVISION HISTORY
6/04—Revision 0: Initial Version
Digital Input/Output Configuration........................................ 21
Multiple Devices on One Bus ................................................... 21
Terminal Voltage Operation Range ......................................... 21
Power-Up and Power-Down Sequences.................................. 21
Layout and Power Supply Biasing ............................................ 22
Digital Potentiometer Operation ............................................. 22
Programmable Rheostat Operation......................................... 22
Programmable Potentiometer Operation ............................... 23
Applications..................................................................................... 24
LCD Panel Vcom Adjustment ..................................................... 24
Current-Sensing Amplifier ....................................................... 24
Adjustable High Power LED Driver ........................................ 24
Outline Dimensions ....................................................................... 25
Ordering Guide .......................................................................... 25
Rev.0 | Page 2 of 28

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AD5251/AD5252
ELECTRICAL CHARACTERISTICS
1 kΩ Version. VDD = 3 V ± 10% or 5 V ± 10%; VSS = 0 V or VDD/VSS = ± 2.5 V ± 10%; VA = +VDD, VB = 0 V, –40°C < TA < +85°C, unless
otherwise noted.
Table 1.
Parameter
Symbol
Conditions
Min Typ1 Max Unit
DC CHARACTERISTICS
RHEOSTAT MODE
Resolution
Resistor Differential
Nonlinearity2
Resistor Nonlinearity2
Nominal Resistor Tolerance
Resistance Temperature
Coefficent
Wiper Resistance
Channel Resistance Matching
DC CHARACTERISTIC
POTENTIOMETER DIVIDER MODE
Differential Nonlinearity3
N
R-DNL
AD5251/AD5252
RWB, RWA = NC, VDD = 5.5 V, AD5251
R-INL
∆RAB/RAB
RWB, RWA = NC, VDD = 5.5 V, AD5252
RWB, RWA = NC, VDD = 2.7 V, AD5251
RWB, RWA = NC, VDD = 2.7 V, AD5252
RWB, RWA = NC, VDD = 5.5 V, AD5251
RWB, RWA = NC, VDD = 5.5 V, AD5252
RWB, RWA = NC, VDD = 2.7 V, AD5251
RWB, RWA = NC, VDD = 2.7 V, AD5252
TA = 25°C
(∆RAB/RAB) × 106/∆T
RW
∆RAB1/∆RAB3
IW = 1 V/R, VDD = 5 V
IW = 1 V/R, VDD = 3 V
DNL AD5251
6/8 Bits
–0.5 ±0.2 +0.5 LSB
–1
–0.75
–1.5
–0.5
–2
–1
–2
–30
±0.25
±0.3
±0.3
±0.2
±0.5
+2.5
+9
+1
+0.75
+1.5
+0.5
+2
+4
+14
+30
LSB
LSB
LSB
LSB
LSB
LSB
LSB
%
650
75 130
200 300
0.15
ppm/°C
%
–0.5 ±0.1 +0.5 LSB
Integral Nonlinearity3
INL
AD5252
AD5251
–1 ±0.25 +1 LSB
–0.5 ±0.2 +0.5 LSB
Voltage Divider Temperature
Coefficent
Full-Scale Error
AD5252
(∆VW/VW) × 106/∆T
VWFSE
Code = half scale
Code = full scale, VDD = 5.5 V, AD5251
Code = full scale, VDD = 5.5 V, AD5252
Code = full scale, VDD = 2.7 V, AD5251
–2 ±0.5 +2 LSB
25
–5 –3 0
–16 –11 0
6 –4 0
ppm/°C
LSB
LSB
LSB
Zero-Scale Error
VWZSE
RESISTOR TERMINALS
Voltage Range4
Capacitance5 Ax, Bx
Capacitance5 Wx
Common-Mode Leakage
Current
DIGITAL INPUTS and OUTPUTS
VA, VB, VW
CA, CB
CW
ICM
Code = full scale, VDD = 2.7 V, AD5252
Code = zero scale, VDD = 5.5 V, AD5251
Code = zero scale, VDD = 5.5 V, AD5252
Code = zero scale, VDD = 2.7 V, AD5251
Code = zero scale, VDD = 2.7 V, AD5252
f = 1 kHz, measured to GND,
Code = half scale
f = 1 kHz, measured to GND,
Code = half scale
VA = VB = VDD/2
–23 –16 0
LSB
0 3 5 LSB
0 11 16 LSB
0 4 6 LSB
0 15 20 LSB
VSS VDD V
85 pF
95 pF
0.01 1
µA
Input Logic High
Input Logic Low
Output Logic High (SDA)
Output Logic Low (SDA)
VIH
VIL
VOH
VOL
VDD = 5 V, VSS = 0 V
VDD/VSS = 2.7 V/0 V or VDD/VSS = ± 2.5 V
VDD = 5V, VSS = 0 V
RPULL-UP = 2.2 kΩ to VDD = 5 V, VSS = 0 V
RPULL-UP = 2.2 kΩ to VDD =5 V, VSS = 0 V
2.4
2.1
4.9
V
V
0.8 V
V
0.4 V
Rev. 0 | Page 3 of 28

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AD5251/AD5252
Parameter
Leakage Current
A0 Leakage Current
Input Leakage Current (Other
than WP and A0)
Input Capacitance5
POWER SUPPLIES
Single-Supply Power Range
Dual-Supply Power Range
Positive Supply Current
Negative Supply Current
Symbol
IWP
IA0
II
CI
VDD
VDD/VSS
IDD
ISS
EEMEM Data Storing Mode
Current
EEMEM Data Restoring Mode
Current6
Power Dissipation7
Power Supply Sensitivity
IDD_STORE
IDD_RESTORE
PDISS
PSS
DYNAMIC CHARACTERISTICS5, 8
Bandwidth –3 dB
Total Harmonic Distortion
VW Settling Time
Resistor Noise Voltage
Digital Crosstalk
Analog Coupling
BW
THD
tS
eN_WB
CT
CAT
Conditions
WP = VDD
A0 = GND
VIN = 0 V or VDD
Min Typ1 Max Unit
5 µA
3 µA
±1 µA
5 pF
VSS = 0 V
VIH = VDD or VIL = GND
VIH = VDD or VIL = GND, VDD = +2.5 V,
VSS = –2.5 V
VIH = VDD or VIL = GND
VIH = VDD or VIL = GND
VIH = VDD = 5 V or VIL = GND
∆VDD = 5 V ± 10%
∆VDD = 3 V ± 10%
2.7
±2.25
5
–5
5.5
±2.75
15
–15
V
V
µA
µA
35 mA
2.5 mA
−0.025 0.01
–0.04 0.02
0.075
0.025
0.04
mW
%/%
%/%
RAB = 1 kΩ
VA = 1 V rms, VB = 0 V, f = 1 kHz
VA = VDD, VB = 0 V
RWB = 500 Ω, f = 1 kHz (thermal noise only)
VA = VDD, VB = 0 V, measure VW with
adjacent RDAC making full-scale change
Signal input at A1 and measure the
output at W3, f = 1 kHz
4 MHz
0.05 %
0.2 µs
3 nV/√Hz
–80 dB
–72 dB
1 Typical represents the average reading at 25°C and VDD = 5 V.
2 Resistor position nonlinearity error (R-INL) is the deviation from an ideal value measured between the maximum resistance and the minimum resistance wiper
positions. R-DNL measures the relative step change from ideal between successive tap positions. Parts are guaranteed monotonic, except R-DNL of AD5252 1 kΩ
version at VDD = 2.7 V, IW = VDD/R for both VDD = 3 V or VDD = 5 V.
3 INL and DNL are measured at VW with the RDAC configured as a potentiometer divider similar to a voltage output D/A converter. VA = VDD and VB = 0 V. DNL
specification limits of ±1 LSB maximum are guaranteed monotonic operating conditions.
4 Resistor Terminals A, B, and W have no limitations on polarity with respect to each other.
5 Guaranteed by design and not subject to production test.
6 cmd 0 NOP should be activated after cmd 1 to minimize IDD_READ current consumption.
7 PDISS is calculated from IDD × VDD = 5 V.
8 All dynamic characteristics use VDD = 5 V.
Rev. 0 | Page 4 of 28

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AD5251/AD5252
10 kΩ, 50 kΩ, 100 kΩ Versions. VDD = +3 V ± 10% or + 5 V ± 10%. VSS = 0 V or VDD/VSS = ± 2.5 V ± 10%. VA = +VDD, VB = 0 V,
–40°C < TA < +85°C, unless otherwise noted.
Table 2.
Parameter
Symbol
Conditions
Min Typ1
Max Unit
DC CHARACTERISTICS
RHEOSTAT MODE
Resolution
N AD5251/AD5252
6/8 Bits
Resistor Differential NL2
R-DNL
RWB, RWA = NC, AD5251
−0.75 ±0.1
+0.75 LSB
Resistor Nonlinearity2
R-INL
RWB, RWA = NC, AD5252
RWB, RWA = NC, AD5251
−1 ±0.25
−0.75 ±0.25
+1 LSB
+0.75 LSB
RWB, RWA = NC, AD5252
−2.5 ±1
+2.5 LSB
Nominal Resistor Tolerance
Resistance Temperature
Coefficent
∆RAB/RAB
TA = 25°C
(∆RAB/RAB) × 106/∆T
−20
650
+20 %
ppm/°C
Wiper Resistance
RW
IW = 1 V/R, VDD = 5 V
75 130 Ω
IW = 1 V/R, VDD = 3 V
200 300 Ω
Channel Resistance Matching ∆RAB1/∆RAB2
RAB = 10 kΩ, 50 kΩ
0.15 %
RAB = 100 kΩ
0.05 %
DC CHARACTERISTICS
POTENTIOMETER DIVIDER
MODE
Differential Nonlinearity3
Integral Nonlinearity
3
Voltage Divider
Temperature Coefficent
Full-Scale Error
Zero-Scale Error
RESISTOR TERMINALS
Voltage Range4
Capacitance5 Ax, Bx
Capacitance5 Wx
Common-Mode Leakage
Current
DIGITAL INPUTS and OUTPUTS
Input Logic High
Input Logic Low
Output Logic High (SDA)
Output Logic Low (SDA)
Leakage Current
A0 Leakage Current
Input Leakage Current
(Other than WP and A0)
Input Capacitance5
POWER SUPPLIES
Single-Supply Power Range
DNL AD5251
AD5252
INL AD5251
AD5252
(∆VW/VW) × 106/∆T
VWFSE
VWZSE
Code = half scale
Code = full scale, AD5251
Code = full scale, AD5252
Code = zero scale, AD5251
Code = zero scale, AD5252
VA, VB, VW
CA, CB
CW
ICM
f = 1 kHz, measured to GND,
Code = half scale
f = 1 kHz, measured to GND,
Code = half scale
VA = VB = VDD/2
−0.5
−1
−0.5
−1.5
−1
−3
0
0
VSS
VIH VDD =5 V, VSS = 0 V
2.4
VDD/VSS = +2.7 V/0 V or VDD/VSS = ±2.5 V 2.1
VIL VDD = 5 V, VSS = 0 V
VDD/VSS = +2.7 V/0 V or VDD/VSS =±2.5 V
VOH
RPULL-UP = 2.2 kΩ to VDD = 5 V, VSS = 0 V
4.9
VOL RPULL-UP = 2.2 kΩ to VDD = 5 V, VSS = 0 V
IWP WP = VDD
IA0 A0 = GND
II VIN = 0 V or VDD
CI
VDD VSS = 0 V
2.7
±0.1
±0.3
±0.15
±0.5
15
−0.3
−1
0.3
1.2
85
95
0.01
5
+0.5 LSB
+1 LSB
+0.5 LSB
+1.5 LSB
ppm/°C
0 LSB
0 LSB
1 LSB
3 LSB
VDD V
pF
pF
1 µA
V
V
0.8 V
0.6 V
V
0.4 V
5 µA
3 µA
±1 µA
pF
5.5 V
Rev. 0 | Page 5 of 28