Single-Supply, Differential, 18-Bit ADC Driver Data Sheet ADA4941-1 FEATURES FUNCTIONAL BLOCK DIAGRAM Single-ended-to-differential converter 1 8 FB IN Excellent linearity Distortion 110 dBc at 100 kHz for VO, dm = 2 V p-p 2 7 REF DIS Low noise: 10.2 nV/Hz, output-referred, G = 2 Extremely low power: 2.2 mA (3 V supply) V+ 3 6 V High input impedance: 24 M User-adjustable gain OUT+ 4 5 OUT High speed: 31 MHz, 3 dB bandwidth (G = +2) Fast settling time: 300 ns to 0.005% for a 2 V step Figure 1. Low offset: 0.8 mV maximum, output-referred, G = 2 Rail-to-rail output Disable feature Wide supply voltage range: 2.7 V to 12 V Available in space-saving, 3 mm 3 mm LFCSP APPLICATIONS Single-supply data acquisition systems Instrumentation Process control Battery-power systems Medical instrumentation GENERAL DESCRIPTION bipolar (XFCB) process, which enables the amplifier to achieve The ADA4941-1 is a low power, low noise differential driver for 18-bit performance on low supply currents. analog-to-digital converters (ADCs) up to 18 bits in systems that are sensitive to power. The ADA4941-1 is configured in an The ADA4941-1 is available in a small 8-lead LFCSP as well as a easy-to-use, single-ended-to-differential configuration and standard 8-lead SOIC and is rated to work over the extended requires no external components for a gain of 2 configuration. industrial temperature range, 40C to +125C. A resistive feedback network can be added to achieve gains greater 60 than 2. The ADA4941-1 provides essential benefits, such as low 65 distortion and high SNR that are required for driving high 70 75 resolution ADCs. V = 6V p-p O 80 85 With a wide input voltage range (0 V to 3.9 V on a single 5 V 90 supply), rail-to-rail output, high input impedance, and a user- 95 100 adjustable gain, the ADA4941-1 is designed to drive single-supply 105 ADCs with differential inputs found in a variety of low power 110 applications, including battery-operated devices and single- V = 2V p-p 115 O HD2 120 HD3 supply data acquisition systems. 125 130 The ADA4941-1 is ideal for driving the 16-bit and 18-bit 135 HD3 HD2 PulSAR ADCs, such as the AD7687, AD7690, and AD7691. 140 0.1 1 10 1000 100 FREQUENCY (kHz) The ADA4941-1 is manufactured on Analog Devices, Inc., Figure 2. Distortion vs. Frequency at Various Output Amplitudes proprietary, second-generation, eXtra fast complementary Rev. D Document Feedback 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 20062016 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Technical Support www.analog.com Trademarks and registered trademarks are the property of their respective owners. DISTORTION (dBc) 05704-001 05704-045ADA4941-1 Data Sheet TABLE OF CONTENTS Features........................................................................................... 1 DC Error Calculations ............................................................ 16 Applications ................................................................................... 1 Output Voltage Noise .............................................................. 17 Functional Block Diagram ............................................................ 1 Frequency Response vs. Closed-Loop Gain .......................... 19 General Description ...................................................................... 1 Applications Information............................................................ 20 Revision History ............................................................................ 2 Overview .................................................................................. 20 Specifications ................................................................................. 3 Using the REF Pin.................................................................... 20 Absolute Maximum Ratings ......................................................... 6 Internal Feedback Network Power Dissipation ..................... 20 Thermal Resistance ................................................................... 6 Disable Feature......................................................................... 20 Maximum Power Dissipation ................................................... 6 Adding a 3-Pole, Sallen-Key Filter.......................................... 21 ESD Caution............................................................................... 6 Driving the AD7687 ADC ...................................................... 22 Pin Configuration and Function Descriptions............................ 7 Gain of 2 Configuration........................................................ 22 Typical Performance Characteristics............................................ 8 Outline Dimensions .................................................................... 23 Theory of Operation.................................................................... 15 Ordering Guide........................................................................ 23 Basic Operation ....................................................................... 15 REVISION HISTORY 5/16Rev. C to Rev. D 8/10Rev. A to Rev. B Change CP-8-2 to CP-8-13 ........................................ Throughout Added Caption to Figure 1.............................................................1 Changes to Figure 4 ........................................................................7 Added Exposed Pad Notation to Figure 4 and Table 6 ................7 Added Figure 5 Renumbered Sequentially ..................................7 Added Exposed Pad Notation to Outline Dimensions ..............23 Updated Outline Dimensions ......................................................23 Changes to Ordering Guide .........................................................23 Changes to Ordering Guide .........................................................23 3/09Rev. 0 to Rev. A 8/11Rev. B to Rev. C Change to Gain Error Drift Parameter, Table 1............................3 Change to Gain Error Drift Unit, Table 1 .....................................3 Change to Gain Error Drift Parameter, Table 2............................4 Change to Gain Error Drift Unit, Table 2 .....................................4 Change to Gain Error Drift Parameter, Table 3............................5 Change to Gain Error Drift Unit, Table 3 .....................................5 Updated Outline Dimensions ......................................................23 4/06Revision 0: Initial Version Rev. D Page 2 of 23