18-Bit, 1.5 LSB INL, 250 kSPS PulSAR Differential ADC in MSOP/LFCSP Data Sheet AD7691 FEATURES APPLICATION DIAGRAM +0.5V TO VDD +2.5V TO +5V 18-bit resolution with no missing codes Throughput: 250 kSPS INL: 0.75 LSB typical, 1.5 LSB maximum (6 ppm of FSR) Dynamic range: 102 dB typical at 250 kSPS VIO +1.8V TO VDD REF VDD IN+ SDI Oversampled dynamic range: 125 dB at1 kSPS 3- OR 4-WIRE SCK INTERFACE 10V, 5V, ... Noise-free code resolution: 20 bits at 1 kSPS SDO IN (SPI, DAISY CHAIN, CS) GND CNV Effective resolution: 22.7 bits at 1 kSPS ADA4941 SINAD: 101.5 dB typical at 1 kHz AD7691 THD: 125 dB typical at 1 kHz Figure 2. True differential analog input range: V REF 0 V to V with V up to VDD on both inputs REF REF No pipeline delay Table 1. MSOP, LFCSP/SOT-23 14-/16-/18-Bit PulSAR ADC Single-supply 2.3 V to 5 V operation with 100 250 400 kSPS to 1000 ADC 1.8 V/2.5 V/3 V/5 V logic interface Type kSPS kSPS 500 kSPS kSPS Driver Proprietary serial interface 18-Bit True AD7691 AD7690 AD7982 ADA4941-1 Differential AD7984 ADA4841-2 SPI/QSPI/MICROWIRE/DSP compatible 16-Bit True AD7684 AD7687 AD7688 ADA4941-1 Ability to daisy-chain multiple ADCs Differential AD7693 ADA4841-2 Optional busy indicator feature 16-Bit AD7680 AD7685 AD7686 AD7980 ADA4841-1 Power dissipation Pseudo AD7683 AD7694 Differential 1.35 mW at 2.5 V/100 kSPS, 4 mW at 5 V/100 kSPS 14-Bit AD7940 AD7942 AD7946 ADA4841-1 1.4 W at 2.5 V/100 SPS Pseudo Standby current: 1 nA Differential 10-lead packages: MSOP (MSOP-8 size) and 3 mm 3 mm LFCSP (SOT-23 size) Pin-for-pin compatible with the18-bit AD7690 and GENERAL DESCRIPTION 16-bit AD7693, AD7688, and AD7687 1 The AD7691 is an 18-bit, charge redistribution, successive approximation, analog-to-digital converter (ADC) that operates APPLICATIONS from a single power supply, VDD, between 2.3 V and 5 V. It Battery-powered equipment contains a low power, high speed, 18-bit sampling ADC with no Data acquisitions missing codes, an internal conversion clock, and a versatile Seismic data acquisition systems serial interface port. On the CNV rising edge, it samples the Instrumentation voltage difference between the IN+ and IN pins. The voltages Medical instruments on these pins swing in opposite phases between 0 V and REF. 1.5 POSITIVE INL = 0.43LSB The reference voltage, REF, is applied externally and can be set NEGATIVE INL = 0.62LSB 1.0 up to the supply voltage. The parts power scales linearly with throughput. 0.5 The SPI-compatible serial interface also features the ability, 0 using the SDI input, to daisy-chain several ADCs on a single 3-wire bus and provides an optional busy indicator. It is compatible 0.5 with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate VIO supply. The AD7691 is housed in a 10-lead MSOP or a 10-lead LFCSP 1.0 with operation specified from 40C to +85C. 1.5 0 65536 131072 196608 262144 1 Protected by U.S. Patent 6,703,961. CODE Figure 1. Integral Nonlinearity vs. Code, 5 V Rev. E 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 20062015 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. INL (LSB) 06146-025 06146-001AD7691 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Driver Amplifier Choice ........................................................... 16 Applications ....................................................................................... 1 Single-to-Differential Driver .................................................... 16 Application Diagram ........................................................................ 1 Voltage Reference Input ............................................................ 16 General Description ......................................................................... 1 Power Supply ............................................................................... 17 Revision History ............................................................................... 2 Supplying the ADC from the Reference .................................. 17 Specif icat ions ..................................................................................... 3 Digital Interface .......................................................................... 17 Timing Specifications .................................................................. 5 CS Mode, 3-Wire Without Busy Indicator ............................. 18 Absolute Maximum Ratings ............................................................ 7 CS Mode, 3-Wire with Busy Indicator .................................... 19 Thermal Resistance ...................................................................... 7 CS Mode, 4-Wire Without Busy Indicator ............................. 20 ESD Caution .................................................................................. 7 CS Mode, 4-Wire with Busy Indicator .................................... 21 Pin Configurations and Function Descriptions ........................... 8 Chain Mode Without Busy Indicator ...................................... 22 Typical Performance Characteristics ............................................. 9 Chain Mode with Busy Indicator ............................................. 23 Terminology .................................................................................... 13 Application Hints ........................................................................... 24 Theory of Operation ...................................................................... 14 Layout .......................................................................................... 24 Circuit Information .................................................................... 14 Evaluating the AD7691 Performance ...................................... 24 Converter Operation .................................................................. 14 Outline Dimensions ....................................................................... 25 Typical Connection Diagram ................................................... 15 Ordering Guide .......................................................................... 25 Analog Inputs .............................................................................. 15 REVISION HISTORY 6/15Rev. D to Rev. E 11/07Rev. 0 to Rev. A Change to Digital Interface Section ............................................. 17 Deleted QFN Package in Development References ....... Universal Change to CS Mode, 3-Wire with Busy Indicator Section ........ 19 Changes to Features, Applications, Figure 1 and Figure 2 ........... 1 Changes to Accuracy, Table 2 .......................................................... 3 CS Change to Mode, 4-Wire with Busy Indicator Section ........ 21 Changes to Power Dissipation, Table 3 ........................................... 4 Changes to the Ordering Guide .................................................... 25 Added Thermal Resistance Section ................................................ 7 Changes to Figure 22...................................................................... 11 7/14Rev. C to Rev. D Changes to Format ......................................................................... 12 Changed QFN (LFCSP) to LFCSP .............................. Throughout Changes to Terminology Section ................................................. 13 Changes to Features Section............................................................ 1 Changes to Format and Figure 29 ................................................ 15 Added Patent Note, Note 1 .............................................................. 1 Inserted Figure 31 ........................................................................... 15 Change to Acquisition Time Parameter, Table 5 .......................... 6 Changes to Format ......................................................................... 17 Changes to Evaluating the AD7691 Performance Section ........ 24 Changes to Figure 44...................................................................... 22 Updated Outline Dimensions ....................................................... 25 Changes to Figure 46...................................................................... 23 Changes to Ordering Guide .......................................................... 25 Updated QFN Outline Dimensions ............................................. 25 Changes to Ordering Guide .......................................................... 25 3/12Rev. B to Rev. C Change to Table 9 ........................................................................... 14 7/06Revision 0: Initial Version Changes to Ordering Guide .......................................................... 25 7/11Rev. A to Rev. B Changes to Common-Mode Input Range Min Parameter ......... 3 Added EPAD Note to Figure 6 and Table 8 ................................... 8 Updated Outline Dimensions ....................................................... 25 Rev. E Page 2 of 28