Precision, Selectable Gain, Fully Differential Funnel Amplifier Data Sheet AD8475 FEATURES FUNCTIONAL BLOCK DIAGRAMS Precision attenuation: G = 0.4, G = 0.8 Fully differential or single-ended input/output Differential output designed to drive precision ADCs Drives switched capacitor and - ADCs Rail-to-rail output 1k +IN 0.4x 1 12 NC VOCM pin adjusts output common-mode voltage 1.25k 1.25k Robust overvoltage protection up to 15 V (V = +5 V) S +IN 0.8x 2 11 OUT Single supply: 3 V to 10 V AD8475 1.25k IN 0.8x 3 10 +OUT Dual supplies: 1.5 V to 5 V 1.25k 1k High performance IN 0.4x 4 9 VOCM Suited for driving 18-bit converters up to 4 MSPS 10 nV/Hz output noise 3 ppm/C gain drift 500 V maximum output offset 50 V/s slew rate NC = NO CONNECT Low power: 3.2 mA supply current Figure 1. 16-Lead LFCSP APPLICATIONS ADC drivers Differential instrumentation amplifier building blocks Single-ended-to-differential converters 1k 1.25k GENERAL DESCRIPTION 1.25k The AD8475 is a fully differential, attenuating amplifier with AD8475 1.25k integrated precision gain resistors. It provides precision attenuation (by 0.4 or 0.8), common-mode level shifting, and single-ended-to- 1.25k 1k differential conversion along with input overvoltage protection. Power dissipation on a single 5 V supply is only 16 mW. The AD8475 is a simple to use, fully integrated precision gain block, designed to process signal levels of up to 10 V on a single NC = NO CONNECT supply. It provides a complete interface to make industrial level Figure 2. 10-Lead MSOP signals directly compatible with the differential input ranges of low voltage high performance 16-bit or 18-bit single-supply successive The AD8475 works extremely well with SAR, -, and pipeline approximation (SAR) analog-to-digital converters (ADCs). converters. The high current output stage of the part allows it to drive the switched capacitor front-end circuits of many ADCs with The AD8475 comes with two standard pin-selectable gain minimal error. options: 0.4 and 0.8. The gain of the part is set by driving the input pin corresponding to the appropriate gain. Unlike many differential drivers in the market, the AD8475 is a high precision amplifier. With 500 V maximum output offset, The AD8475 also provides overvoltage protection from large 10 nV/Hz output noise, and 112 dB THD + N, the AD8475 industrial input voltages up to 15 V while operating on a single pairs well with high accuracy converters. Considering its low power 5 V supply. The VOCM pin adjusts the output voltage common consumption and high precision, the slew-enhanced AD8475 has mode for precision level shifting, to match the ADCs input range excellent speed, settling to 18-bit precision for 4 MSPS acquisition. and maximize dynamic range. The AD8475 is available in a space-saving 16-lead 3 mm 3 mm LFCSP package and a 10-lead MSOP package. It is fully specified over the 40C to +85C temperature range. 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 20102017 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Technical Support www.analog.com IN 0.8x 1 10 +IN 0.8x IN 0.4x 2 9 +IN 0.4x +V 3 8 V S S VOCM 4 7 NC +OUT 5 6 OUT 09432-002 09432-001 IN 0.4x 5 16 +IN 0.4x +V 6 15 V S S 14 V +V 7 S S 8 13 +V V S SAD8475 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Circuit Information .................................................................... 17 Applications ....................................................................................... 1 DC Precision ............................................................................... 17 General Description ........................................................................... 1 Input Voltage Range ................................................................... 18 Functional Block Diagrams ............................................................. 1 Driving the AD8475................................................................... 18 Revision History ............................................................................... 2 Power Supplies ............................................................................ 18 Specifications ..................................................................................... 3 Applications Information .............................................................. 19 Absolute Maximum Ratings ............................................................ 5 Typical Configuration ................................................................ 19 Thermal Resistance ...................................................................... 5 Single-Ended to Differential Conversion ................................ 19 ESD Caution .................................................................................. 5 Setting the Output Common-Mode Voltage .......................... 19 Pin Configurations and Function Descriptions ........................... 6 High Performance ADC Driving ............................................. 20 Typical Performance Characteristics ............................................. 8 AD8475 Evaluation Board ............................................................ 22 Terminology .................................................................................... 16 Outline Dimensions ....................................................................... 23 Theory of Operation ...................................................................... 17 Ordering Guide .......................................................................... 24 Overview ...................................................................................... 17 REVISION HISTORY 4/2011Rev. A to Rev. B 3/2017Rev. C to Rev. D Added B Grade Columns to Specifications Section ..................... 3 Changes to Figure 3 .......................................................................... 6 Changes to Figure 16 ......................................................................... 9 Updated Outline Dimensions ....................................................... 23 Changes to Figure 43 ...................................................................... 14 Changes to Ordering Guide .......................................................... 24 Changes to Ordering Guide .......................................................... 24 1/2014Rev. B to Rev. C 1/2011Rev. 0 to Rev. A Changed Minimum B Grade Output Balance Error from 90 dB Added 16-Lead LFCSP ................................................. Throughout to 90 dB ............................................................................................ 3 Changes to Table 1 and Note 3 ........................................................ 3 Changes to Endnote 3 Table 1 ........................................................ 4 Change to Table 2 .............................................................................. 5 Changes to Terminology Section.................................................. 16 Added Figure 3 and Table 4 Renumbered Sequentially .............. 6 Changes to Input Voltage Range Section and Figure 51 ........... 18 Changes to Typical Performance Characteristics Format ............ 8 Changes to Single-Ended to Differential Conversion Section Added AD8475 Evaluation Board Section and Figure 56 ......... 22 and Setting the Output Common-Mode Voltage Section ......... 19 Changes to Figure 56 ...................................................................... 22 10/2010Revision 0: Initial Version Rev. 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