1-/2-/4-Channel Digital Potentiometers AD8400/AD8402/AD8403 FEATURES FUNCTIONAL BLOCK DIAGRAM 256-position variable resistance device RDAC1 8 A1 AD8403 Replaces 1, 2, or 4 potentiometers 8-BIT V LATCH W1 DD 1 k, 10 k , 50 k, 100 k DAC B1 CK RS SELECT DGND AGND1 SHDN Power shutdownless than 5 A 1 2 RDAC2 3-wire,SPI-compatible serial data input A2 8 8-BIT 3 W2 10 MHz update data loading rate LATCH 4 B2 A1, A0 CK RS 2.7 V to 5.5 V single-supply operation SHDN AGND2 2 Qualified for automotive applications 10-BIT RDAC3 A3 8 8 SERIAL 8-BIT LATCH W3 LATCH B3 APPLICATIONS SDI D CK RS SHDN AGND3 CK Q RS Mechanical potentiometer replacement CLK RDAC4 A4 8 8-BIT Programmable filters, delays, time constants CS W4 LATCH B4 Volume control, panning CK RS AGND4 SHDN Line impedance matching Power supply adjustment SDO RS SHDN Figure 1. GENERAL DESCRIPTION The AD8400/AD8402/AD8403 provide a single-, dual-, or 100 quad-channel, 256-position, digitally controlled variable resistor 1 (VR) device. These devices perform the same electronic adjust- R R WA WB ment function as a mechanical potentiometer or variable 75 resistor. The AD8400 contains a single variable resistor in the compact SOIC-8 package. The AD8402 contains two independent variable resistors in space-saving SOIC-14 surface-mount 50 packages. The AD8403 contains four independent variable resistors in 24-lead PDIP, SOIC, and TSSOP packages. Each part contains a fixed resistor with a wiper contact that taps the 25 fixed resistor value at a point determined by the digital code loaded into the controlling serial input register. The resistance between the wiper and either endpoint of the fixed resistor 0 varies linearly with respect to the digital code transferred into 0 64 128 192 255 CODE (Decimal) the VR latch. Each variable resistor offers a completely programmable value of resistance between the A terminal and Figure 2. R and R vs. Code WA WB the wiper or the B terminal and the wiper. The fixed A-to-B terminal resistance of 1 k, 10 k, 50 k, or 100 k has a 1% channel-to-channel matching tolerance with a nominal temperature coefficient of 500 ppm/C. A unique switching circuit minimizes the high glitch inherent in traditional switched resistor designs, avoiding any make-before-break or break-before-make operation. (continued on Page 3) 1 The terms digital potentiometer, VR, and RDAC are used interchangeably. Rev. E 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. R (D), R (D) (% of Nominal R ) WA WB AB 01092-002 01092-001AD8400/AD8402/AD8403 TABLE OF CONTENTS Features .............................................................................................. 1 ESD Caution................................................................................ 11 Applications ....................................................................................... 1 Pin Configurations and Function Descriptions ......................... 12 General Description ......................................................................... 1 Typical Performance Characteristics ........................................... 14 Functional Block Diagram .............................................................. 1 Test Circuits ..................................................................................... 19 Revision History ............................................................................... 2 Theory of Operation ...................................................................... 20 Specif icat ions ..................................................................................... 4 Programming the Variable Resistor ......................................... 20 Electrical Characteristics10 k Version ................................ 4 Programming the Potentiometer Divider ............................... 21 Electrical Characteristics50 k and 100 k Versions ......... 6 Digital Interfacing ...................................................................... 21 Electrical Characteristics1 k Version .................................. 8 Applicat ions ..................................................................................... 24 Electrical CharacteristicsAll Versions ................................. 10 Active Filter ................................................................................. 24 Timing Diagrams ........................................................................ 10 Outline Dimensions ....................................................................... 26 Absolute Maximum Ratings .......................................................... 11 Ordering Guide .......................................................................... 30 Serial Data-Word Format .......................................................... 11 Automotive Products ................................................................. 31 REVISION HISTORY 7/10Rev. D to Rev. E 11/01Rev. B to Rev. C Changes to Features Section ............................................................ 1 Addition of new Figure ..................................................................... 1 Changes to IAB Continuous Current Parameter (Table 5) ......... 11 Edits to Specifications ....................................................................... 2 Updated Outline Dimensions ........................................................ 26 Edits to Absolute Maximum Ratings .............................................. 6 Changes to Ordering Guide ........................................................... 30 Edits to TPCs 1, 8, 12, 16, 20, 24, 35 ............................................... 9 Added Automotive Products Section ........................................... 31 Edits to the Programming the Variable Resistor Section .......................... 13 10/05Rev. C to Rev. D Updated Format .................................................................. Universal Changes to Features ........................................................................... 1 Changes to Table 1 ............................................................................. 4 Changes to Table 2 ............................................................................. 6 Changes to Table 3 ............................................................................. 8 Changes to Table 5 ........................................................................... 11 Added Figure 36 ............................................................................... 18 Replaced Figure 37 .......................................................................... 19 Changes to Theory of Operation Section ..................................... 20 Changes to Applications Section ................................................... 24 Updated Outline Dimensions ........................................................ 26 Changes to Ordering Guide ........................................................... 28 Rev. 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