Single-Channel, 1024-Position, Digital Rheostat with SPI Interface and 50-TP Memory AD5174 FEATURES FUNCTIONAL BLOCK DIAGRAM V DD Single-channel, 1024-position resolution 10 k nominal resistance 50-times programmable (50-TP) wiper memory POWER-ON RESET Rheostat mode temperature coefficient: 35 ppm/C AD5174 2.7 V to 5.5 V single-supply operation 2.5 V to 2.75 V dual-supply operation for ac or bipolar RDAC operations SCLK REGISTER A 10 SPI-compatible interface SPI SYNC SERIAL Wiper setting and memory readback W INTERFACE Power on refreshed from memory 50-TP DIN MEMORY Resistor tolerance stored in memory BLOCK SDO Thin LFCSP 10-lead, 3 mm 3 mm 0.8 mm package Compact MSOP, 10-lead, 3 mm 4.9 mm 1.1 mm package APPLICATIONS V EXT CAP GND SS Figure 1. Mechanical rheostat replacements Op-amp: variable gain control Instrumentation: gain, offset adjustment Programmable voltage-to-current conversions Programmable filters, delays, time constants Programmable power supply Sensor calibration GENERAL DESCRIPTION The AD5174 is a single-channel, 1024-position digital rheostat The AD5174 device wiper settings are controllable through the that combines industry leading variable resistor performance SPI digital interface. Unlimited adjustments are allowed before with nonvolatile memory (NVM) in a compact package. programming the resistance value into the 50-TP memory. The AD5174 does not require any external voltage supply to facili- This device supports both dual-supply operation at 2.5 V to tate fuse blow and there are 50 opportunities for permanent 2.75 V and single-supply operation at 2.7 V to 5.5 V and offers programming. During 50-TP activation, a permanent blow fuse 50-times programmable (50-TP) memory. command freezes the resistance position (analogous to placing epoxy on a mechanical rheostat). The AD5174 is available in a 3 mm 3mm 10-lead LFCSP package and in a 10-lead MSOP package. The part is guaranteed to operate over the extended industrial temperature range of 40C to +125C. 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 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. 08718-001AD5174 TABLE OF CONTENTS Features .............................................................................................. 1 Shift Register............................................................................... 12 Applications....................................................................................... 1 RDAC Register............................................................................ 12 Functional Block Diagram .............................................................. 1 50-TP Memory Block ................................................................ 12 General Description ......................................................................... 1 Write Protection ......................................................................... 12 Revision History ............................................................................... 2 RDAC and 50-TP Read Operation .......................................... 13 Specifications..................................................................................... 3 Shutdown Mode ......................................................................... 14 Electrical Characteristics............................................................. 3 Reset ............................................................................................. 14 Interface Timing Specifications.................................................. 4 SDO Pin and Daisy-Chain Operation..................................... 15 Absolute Maximum Ratings............................................................ 6 RDAC Architecture.................................................................... 16 Thermal Resistance ...................................................................... 6 Programming the Variable Resistor......................................... 16 ESD Caution.................................................................................. 6 EXT CAP Capacitor.................................................................. 17 Pin Configuration and Function Descriptions............................. 7 Terminal Voltage Operating Range ......................................... 17 Typical Performance Characteristics ............................................. 8 Power-Up Sequence ................................................................... 17 Test Circuits..................................................................................... 11 Outline Dimensions....................................................................... 18 Theory of Operation ...................................................................... 12 Ordering Guide .......................................................................... 18 Serial Data Interface................................................................... 12 REVISION HISTORY 12/10Rev. A to Rev. B Changes to SDO Pin Description................................................... 7 Changes to SDO Pin and Daisy-Chain Operation Section....... 15 7/10Rev. 0 to Rev. A Changes to Daisy-Chain Operation Section including Changing Title to SDO Pin and Daisy-Chain Operation Section ............. 15 Added Table 11 ............................................................................... 15 Changes to Ordering Guide .......................................................... 18 3/10Revision 0: Initial Version Rev. B Page 2 of 20