24-Bit, 8.5 mW, 109 dB, 128 kSPS/64 kSPS/32 kSPS ADCs AD7766 FEATURES GENERAL DESCRIPTION Oversampled successive approximation (SAR) architecture The AD7766/AD7766-1/AD7766-2 are high performance, High performance ac and dc accuracy, low power 24-bit, oversampled SAR analog-to-digital converters (ADCs). 115.5 dB dynamic range, 32 kSPS (AD7766-2) The AD7766/AD7766-1/AD7766-2 combine the benefits of a 112.5 dB dynamic range, 64 kSPS (AD7766-1) large dynamic range and input bandwidth, consuming 15 mW, 109.5 dB dynamic range, 128 kSPS (AD7766) 10.5 mW, and 8.5 mW power, respectively, and are contained in 112 dB THD a 16-lead TSSOP package. Exceptionally low power Ideal for ultralow power data acquisition (such as PCI- and USB- 8.5 mW, 32 kSPS (AD7766-2) based systems), the AD7766/AD7766-1/AD7766-2 provide 24-bit 10.5 mW, 64 kSPS (AD7766-1) resolution. The combination of exceptional SNR, wide dynamic 15 mW, 128 kSPS (AD7766) range, and outstanding dc accuracy make the AD7766/AD7766-1/ High dc accuracy AD7766-2 ideally suited for measuring small signal changes over a 24 bits, no missing codes (NMC) wide dynamic range. This is particularly suitable for applications INL: 6 ppm (typical), 15 ppm (maximum) where small changes on the input are measured on larger ac or Low temperature drift dc signals. In such an application, the AD7766/AD7766-1/ Zero error drift: 15 nV/C AD7766-2 accurately gather both ac and dc information. Gain error drift: 0.4 ppm/C The AD7766/AD7766-1/AD7766-2 include an on-board digital On-chip low-pass FIR filter filter (complete with linear phase response) that acts to elimi- Linear phase response nate out-of-band noise by filtering the oversampled input voltage. Pass-band ripple: 0.005 dB The oversampled architecture also reduces front-end antialias Stop-band attenuation: 100 dB requirements. Other features of the AD7766/AD7766-1/AD7766-2 2.5 V supply with 1.8 V/2.5 V/3 V/3.6 V logic interface options SYNC PD Flexible interfacing options include a / (synchronization/power-down) pin, allowing Synchronization of multiple devices the synchronization of multiple AD7766/AD7766-1/AD7766-2 Daisy-chain capability devices. The addition of an SDI pin provides the option of daisy Power-down function chaining multiple AD7766/AD7766-1/AD7766-2 devices. Temperature range: 40C to +105C The AD7766/AD7766-1/AD7766-2 operate from a 2.5 V supply using a 5 V reference. The devices operate from 40C to +105C. APPLICATIONS Low power PCI/USB data acquisition systems RELATED DEVICES Low power wireless acquisition systems Table 1. 24-Bit ADCs Vibration analysis Part No. Description Instrumentation 1 AD7760 2.5 MSPS, 100 dB dynamic range, on-board differential High precision medical acquisition amp and reference buffer, parallel, variable decimation 1 AD7762/ FUNCTIONAL BLOCK DIAGRAM 625 kSPS, 109 dB dynamic range, on-board differential AD7763 amp and reference buffer, parallel/serial, variable AV AGND MCLK DV V DGND DD DD DRIVE decimation 1 V AD7764 312 kSPS, 109 dB dynamic range, on-board differential REF+ amp and reference buffer, variable decimation (pin) V IN+ 1 DIGITAL AD7765 SUCCESSIVE 156 kSPS, 112 dB dynamic range, on-board differential FIR FILTER APPROXIMATION amp and reference buffer, variable decimation (pin) ADC SYNC/PD 1 V AD7767 IN 128 kSPS, 109.5 dB, 15 mW, 18-bit INL, serial interface SERIAL INTERFACE 1 REFGND AND CS AD7767-1 64 kSPS 112.5 dB, 10.5 mW, 18-bit INL, serial interface CONTROL LOGIC AD7766/ 1 AD7767-2 32 kSPS, 115.5 dB, 8.5 mW, 18-bit INL, serial interface AD7766-1/ AD7766-2 1 Dynamic range at maximum output data rate. SCLK DRDY SDO SDI Figure 1. Rev. C 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 20072010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 06449-001AD7766 TABLE OF CONTENTS Features .............................................................................................. 1 Supply and Reference Voltages ................................................. 16 Applications ....................................................................................... 1 AD7766/AD7766-1/AD77662-2 Interface .................................. 17 Functional Block Diagram .............................................................. 1 Initial Power-Up ......................................................................... 17 General Description ......................................................................... 1 Reading Data ............................................................................... 17 Related Devices ................................................................................. 1 Power-Down, Reset, and Synchronization ............................. 17 Revision History ............................................................................... 2 Daisy Chaining ............................................................................... 18 Specif icat ions ..................................................................................... 3 Reading Data in Daisy-Chain Mode ....................................... 18 Timing Specifications .................................................................. 5 Choosing the SCLK Frequency ................................................ 18 Timing Diagrams .......................................................................... 6 Daisy-Chain Mode Configuration and Timing Diagrams ... 19 Absolute Maximum Ratings ............................................................ 8 Driving the AD7766/AD7766-1/AD7766-2 ............................... 20 ESD Caution .................................................................................. 8 Differential Signal Source ......................................................... 20 Pin Configuration and Function Descriptions ............................. 9 Single-Ended Signal Source ...................................................... 20 Typical Performance Characteristics ........................................... 10 Antialiasing ................................................................................. 21 Terminology .................................................................................... 14 Power Dissipation....................................................................... 21 Theory of Operation ...................................................................... 15 V Input Signal ....................................................................... 22 REF+ AD7766/AD7766-1/AD7766-2 Transfer Function ................ 15 Multiplexing Analog Input Channels ...................................... 22 Converter Operation .................................................................. 15 Outline Dimensions ....................................................................... 23 Analog Input Structure .............................................................. 16 Ordering Guide .......................................................................... 23 REVISION HISTORY 4/10Rev. B to Rev. C Changes to Pin 8 Description ......................................................... 9 Changes to Table 8 .......................................................................... 20 3/09Rev. A to Rev. B Changes to t Parameter, Table 3 .......................................... 5 SETTLING Changes to Table 7 .......................................................................... 17 1/09Rev. 0 to Rev. A Changes to Features Section............................................................ 1 Change to AD7766, Intermodulation Distortion (IMD) Parameter and Integral Nonlinearity Parameter, Table 2 ....... 3 Change to Figure 21 and Figure 24 .............................................. 12 Changes to Supply and Reference Voltages Section ................... 16 Changes to Choosing the SCLK Frequency Section .................. 18 Changes to Driving the AD7766 Section .................................... 20 Changes to Single-Ended Signal Source Section ........................ 20 Changes to Figure 40 and Figure 41 ............................................. 20 Added Table 8 Renumbered Sequentially .................................. 20 Change to Figure 42 ....................................................................... 21 Changes to Antialiasing Section ................................................... 21 Changes to Table 9 .......................................................................... 21 Changes to V REF+ Input Signal Section ......................................... 22 Changes to Figure 46 ...................................................................... 22 8/07Revision 0: Initial Version Rev. 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