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Analog Devices |
FEATURES
256-position
End-to-end resistance 5 kΩ, 10 kΩ, 50 kΩ, 100 kΩ
Compact SOT-23-8 (2.9 mm × 3 mm) package
Fast settling time: tS = 5 µs typ on power-up
Full read/write of wiper register
Power-on preset to midscale
Extra package address decode pin AD0
Computer software replaces µC in factory programming
applications
Single supply: 2.7 V to 5.5 V
Low temperature coefficient 45 ppm/°C
Low power: IDD = 8 µA
Wide operating temperature: –40°C to +125°C
Evaluation board available
APPLICATIONS
Mechanical potentiometer replacement in new designs
LCD panel VCOM adjustment
LCD panel brightness and contrast control
Transducer adjustment of pressure, temperature, position,
chemical, and optical sensors
RF amplifier biasing
Automotive electronics adjustment
Gain control and offset adjustment
GENERAL DESCRIPTION
The AD5245 provides a compact 2.9 mm × 3 mm packaged
solution for 256-position adjustment applications. These
devices perform the same electronic adjustment function as
mechanical potentiometers or variable resistors, with enhanced
resolution, solid-state reliability, and superior low temperature
coefficient performance.
The wiper settings are controllable through an I2C-compatible
digital interface, which can also be used to read back the wiper
register content. AD0 can be used to place up to two devices on
the same bus. Command bits are available to reset the wiper
position to midscale or to shut down the device into a state of
zero power consumption.
256-Position I2C®-Compatible
Digital Potentiometer
AD5245
FUNCTIONAL BLOCK DIAGRAM
VDD
SCL
SDA
AD0
I2C INTERFACE
A
W
WIPER
REGISTER
POR
GND
Figure 1.
B
PIN CONFIGURATION
W1
8A
VDD 2 AD5245 7 B
GND 3 TOP VIEW 6 AD0
SCL 4 (Not to Scale) 5 SDA
Figure 2.
Operating from a 2.7 V to 5.5 V power supply and consuming
less than 8 µA allows usage in portable battery-operated
applications.
Note that the terms digital potentiometer, VR, and RDAC are
used interchangeably.
Rev. B
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.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2006 Analog Devices, Inc. All rights reserved.
AD5245
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
Functional Block Diagram .............................................................. 1
Pin Configuration............................................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Electrical Characteristics ................................................................. 3
5 kΩ Version.................................................................................. 3
10 kΩ, 50 kΩ, 100 kΩ Versions .................................................. 4
Timing Characteristics..................................................................... 5
5 kΩ, 10 kΩ, 50 kΩ, 100 kΩ Versions........................................ 5
Absolute Maximum Ratings............................................................ 6
ESD Caution.................................................................................. 6
Pin Configuration and Function Descriptions............................. 7
Typical Performance Characteristics ............................................. 8
Test Circuits..................................................................................... 12
Theory of Operation ...................................................................... 13
Programming the Variable Resistor......................................... 13
Programming the Potentiometer Divider............................... 14
ESD Protection ........................................................................... 14
Terminal Voltage Operating Range ......................................... 14
Power-Up Sequence ................................................................... 14
Layout and Power Supply Bypassing ....................................... 14
Constant Bias to Retain Resistance Setting............................. 15
Evaluation Board ........................................................................ 15
I2C Interface .................................................................................... 16
I2C-Compatible 2-Wire Serial Bus........................................... 16
Outline Dimensions ....................................................................... 19
Ordering Guide .......................................................................... 19
REVISION HISTORY
1/06—Rev. A to Rev. B
Changes to Table 3........................................................................... 5
Changes to Ordering Guide ......................................................... 19
3/04—Rev. 0 to Rev. A
Updated Format................................................................ Universal
Changes to Features......................................................................... 1
Changes to Applications ................................................................. 1
Changes to Figure 1......................................................................... 1
Changes to Electrical Characteristics—5 kΩ Version ................ 3
Changes to Electrical Characteristics—10 kΩ, 50 kΩ,
and 100 kΩ Versions ....................................................................... 4
Changes to Timing Characteristics ............................................... 5
Changes to Absolute Maximum Ratings ...................................... 6
Moved ESD Caution to Page .......................................................... 6
Changes to Pin Configuration and Function Descriptions ....... 7
Changes to Figures 22 and 23 ...................................................... 11
Moved Figure 25 to Figure 26 ...................................................... 11
Moved Figure 26 to Figure 27 ...................................................... 11
Moved Figure 27 to Figure 25 ...................................................... 11
Deleted Figures 31 and 32 ............................................................ 12
Changes to Figure 32, Figure 33 and Figure 34 ......................... 12
Changes to Rheostat Operation Section..................................... 13
Added Figure 35............................................................................. 13
Changes to Equation 1 and Equation 2 ...................................... 13
Changes to Table 6 and Table 7.................................................... 13
Added Figure 37 ............................................................................ 14
Changes to Equation 4 .................................................................. 14
Deleted Readback RDAC Value Section .................................... 14
Deleted Level Shifting for Bidirectional Interface Section ...... 14
Moved ESD Protection Section to Page ..................................... 14
Changes to Figure 38 and Figure 39............................................ 14
Moved Terminal Voltage Operating Range Section to Page.... 14
Changes to Figure 40..................................................................... 14
Moved Power-Up Sequence Section to Page ............................. 14
Moved Layout and Power Supply Bypassing Section to Page . 15
Added Constant Bias to Retain Resistance Setting Section..... 15
Added Figure 42 ............................................................................ 15
Added Evaluation Board Section ................................................ 15
Added Figure 43 ............................................................................ 15
Moved I2C Interface Section to Page........................................... 16
Changes to I2C Compatible 2-Wire Serial Bus Section ........... 16
Moved Table 5 and Table 6 to Page ............................................. 17
(Renumbered as Table 8 and Table 9)
Moved Figure 36, Figure 37, and Figure 38 to Page.................. 17
(Renumbered as Figure 44, Figure 45, and Figure 46)
Moved Multiply Devices on One Bus Section to Page ............. 18
Updated Ordering Guide ............................................................. 19
Updated Outline Dimensions...................................................... 19
Moved I2C Disclaimer to Page ..................................................... 20
5/03—Revision 0: Initial Version
Rev. B | Page 2 of 20
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