64-Position Up/Down Control Digital Potentiometer AD5227 FEATURES FUNCTIONAL BLOCK DIAGRAM V 64-position digital potentiometer DD 10 k, 50 k, 100 k end-to-end terminal resistance AD5227 Simple up/down digital or manual configurable control A Midscale preset CS 6-BIT UP/DOWN Low potentiometer mode tempco = 10 ppm/C U/D CONTROL W LOGIC Low rheostat mode tempco = 35 ppm/C CLK B Ultralow power, IDD = 0.4 A typ and 3 A max Fast adjustment time, ts = 1 s GND POR WIPER Chip select enable multiple device operation MIDSCALE REGISTER Low operating voltage, 2.7 V to 5.5 V Automotive temperature range, 40C to +105C Figure 1. Compact thin SOT-23-8 (2.9 mm 3 mm) Pb-free package APPLICATIONS Mechanical potentiometer and trimmer replacements LCD backlight, contrast, and brightness controls Portable electronics level adjustment Programmable power supply Digital trimmer replacements Automatic closed-loop control GENERAL DESCRIPTION The AD5227 is Analog Devices latest 64-step up/down control The AD5227 is available in a compact thin SOT-23-8 (TSOT-8) 1 digital potentiometer . This device performs the same electronic Pb-free package. The part is guaranteed to operate over the adjustment function as a 5 V potentiometer or variable resistor. automotive temperature range of 40C to +105C. Its simple 3-wire up/down interface allows manual switching or Users who consider EEMEM potentiometers should refer to high speed digital control. The AD5227 presets to midscale at some recommendations in the Applications section. power-up. When CS is enabled, the devices changes step at Table 1. Truth Table every clock pulse. The direction is determined by the state of 1 CS U/D the U/D pin (see Table 1). The interface is simple to activate by CLK Operation any host controller, discrete logic, or manually with a rotary 0 0 RWB Decrement encoder or pushbuttons. The AD5227s 64-step resolution, small 0 1 RWB Increment footprint, and simple interface enable it to replace mechanical 1 X X No Operation potentiometers and trimmers with typically 6 improved 1 RWA increments if RWB decrements and vice versa. resolution, solid-state reliability, and design layout flexibility, resulting in a considerable cost savings in end users systems. 1 The terms digital potentiometer 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. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Specifications subject to change without notice. No license is granted by implication Tel: 781.329.4700 www.analog.com or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781.326.8703 20042009 Analog Devices, Inc. All rights reserved. 04419-0-001AD5227 TABLE OF CONTENTS Electrical Characteristics ................................................................. 3 Applicat ions ..................................................................................... 12 Interface Timing Diagrams ......................................................... 4 Manual Control with Toggle and Pushbutton Switches ........ 12 Absolute Maximum Ratings ............................................................ 5 Manual Control with Rotary Encoder ..................................... 12 ESD Caution .................................................................................. 5 Adjustable LED Driver .............................................................. 12 Pin Configuration and Function Descriptions ............................. 6 Adjustable Current Source for LED Driver ............................ 12 Typical Performance Characteristics ............................................. 7 Adjustable High Power LED Driver ........................................ 13 Theory of Operation ...................................................................... 10 Automatic LCD Panel Backlight Control ................................ 13 Programming the Digital Potentiometers ............................... 10 6-Bit Controller .......................................................................... 13 Digital Interface .......................................................................... 11 Constant Bias with Supply to Retain Resistance Setting ....... 14 Terminal Voltage Operation Range ......................................... 11 Outline Dimensions ....................................................................... 15 Power-Up and Power-Down Sequences .................................. 11 Ordering Guide .......................................................................... 15 Layout and Power Supply Biasing ............................................ 11 REVISION HISTORY 5/09Rev. A to Rev. B Changes to Table 23 4/09Rev. 0 to Rev. A Changes to Table 23 Changes to Ordering Guide 15 3/04Revision 0: Initial Version Rev. B Page 2 of 16