11 mW Power, 2.3 V to 5.5 V, Complete DDS AD9838 Capability for phase modulation and frequency modulation is FEATURES provided. The frequency registers are 28 bits wide: with a 16 MHz 2.3 V to 5.5 V power supply clock rate, resolution of 0.06 Hz can be achieved with a 5 MHz MCLK speed: 16 MHz (B grade), 5 MHz (A grade) clock rate, the AD9838 can be tuned to 0.02 Hz resolution. Output frequency up to 8 MHz Frequency and phase modulation are configured by loading Sinusoidal and triangular outputs registers through the serial interface and by toggling the registers On-board comparator using software or the FSELECT and PSELECT pins, respectively. 3-wire SPI interface Extended temperature range: 40C to +125C The AD9838 is written to via a 3-wire serial interface. This serial Power-down option interface operates at clock rates up to 40 MHz and is compatible 11 mW power consumption at 2.3 V with DSP and microcontroller standards. 20-lead LFCSP The device operates with a power supply from 2.3 V to 5.5 V. The analog and digital sections are independent and can be run from APPLICATIONS different power supplies for example, AVDD can equal 5 V with Frequency stimulus/waveform generation DVDD equal to 3 V. Frequency phase tuning and modulation Low power RF/communications systems The AD9838 has a power-down pin (SLEEP) that allows external Liquid and gas flow measurement control of the power-down mode. Sections of the device that are Sensory applications: proximity, motion, and defect detection not being used can be powered down to minimize current con- Test and medical equipment sumption. For example, the DAC can be powered down when a clock output is being generated. GENERAL DESCRIPTION The AD9838 is available in a 20-lead LFCSP WQ package. The AD9838 is a low power DDS device capable of producing high performance sine and triangular outputs. It also has an on-board comparator that allows a square wave to be produced for clock generation. Consuming only 11 mW of power at 2.3 V, the AD9838 is an ideal candidate for power-sensitive applications. FUNCTIONAL BLOCK DIAGRAM AVDD AGND DGND DVDD CAP/2.5V REFOUT FSADJUST REGULATOR ON-BOARD REFERENCE MCLK VCC FULL-SCALE 2.5V COMP CONTROL FSELECT 28-BIT FREQ0 REG 12 PHASE IOUT SIN 10-BIT MUX ACCUMULATOR MUX ROM DAC (28-BIT) IOUTB 28-BIT FREQ1 REG MSB 12-BIT PHASE0 REG MUX MUX 12-BIT PHASE1 REG DIVIDE BY 2 16-BIT CONTROL MUX SIGN BIT OUT REGISTER SERIAL INTERFACE COMPARATOR VIN AND CONTROL LOGIC AD9838 FSYNC SCLK SDATA PSELECT SLEEP RESET Figure 1. Rev. A 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 2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 09077-001AD9838 TABLE OF CONTENTS Features .............................................................................................. 1 Functional Description.................................................................. 17 Applications....................................................................................... 1 Serial Interface ............................................................................ 17 General Description ......................................................................... 1 Latency Period ............................................................................ 17 Functional Block Diagram .............................................................. 1 Control Register ......................................................................... 17 Revision History ............................................................................... 2 Frequency and Phase Registers ................................................ 19 Specifications..................................................................................... 3 Reset Function ............................................................................ 20 Timing Characteristics ................................................................ 5 Sleep Function ............................................................................ 20 Absolute Maximum Ratings............................................................ 6 SIGN BIT OUT Pin.................................................................... 21 Thermal Resistance ...................................................................... 6 IOUT and IOUTB Pins ............................................................. 21 ESD Caution.................................................................................. 6 Powering Up the AD9838 ......................................................... 21 Pin Configuration and Function Descriptions............................. 7 Applications Information .............................................................. 24 Typical Performance Characteristics ............................................. 9 Grounding and Layout .............................................................. 24 Test Circuit ...................................................................................... 12 Interfacing to Microprocessors................................................. 24 Terminology .................................................................................... 13 Evaluation Board ............................................................................ 26 Theory of Operation ...................................................................... 14 System Demonstration Platform.............................................. 26 Circuit Description......................................................................... 15 AD9838 to SPORT Interface..................................................... 26 Numerically Controlled Oscillator Plus Phase Modulator ... 15 Evaluation Kit ............................................................................. 26 SIN ROM ..................................................................................... 15 Crystal Oscillator vs. External Clock....................................... 26 Digital-to-Analog Converter (DAC) ....................................... 15 Power Supply............................................................................... 26 Comparator ................................................................................. 15 Evaluation Board Schematics ................................................... 27 Regulator...................................................................................... 16 Evaluation Board Layout........................................................... 29 Outline Dimensions ....................................................................... 30 Ordering Guide .......................................................................... 30 REVISION HISTORY 4/11Rev. 0 to Rev. A Change to Title.................................................................................. 1 Change to Figure 3 ........................................................................... 5 Change to Figure 8 ........................................................................... 9 4/11Revision 0: Initial Version Rev. A Page 2 of 32