14-Bit, 500 kSPS, PulSAR ADC in MSOP and LFCSP Data Sheet AD7946 FEATURES TYPICAL APPLICATION CIRCUIT 0.5V TO 5V 5V 14-bit resolution with no missing codes Throughput: 500 kSPS INL: 0.4 LSB typical, 1 LSB maximum (0.0061% of FSR) VIO 1.8V TO VDD SINAD: 85 dB at 20 kHz REF VDD 0V TO REF SDI THD: 100 dB at 20 kHz IN+ SCK AD7946 3- OR 4-WIRE INTERFACE Pseudo differential analog input range IN (SPI, DAISY CHAIN, CS) SDO 0 V to REF with REF up to VDD GND CNV No pipeline delay Single-supply 5 V operation with 1.8 V/2.5 V/3 V/5 V logic Figure 1. interface GENERAL DESCRIPTION Proprietary serial interface 1 SPI-/QSPI-/MICROWIRE-/DSP-compatible The AD7946 is a 14-bit, charge redistribution, successive Daisy-chain multiple ADCs and BUSY indicator approximation, analog-to-digital converter (ADC) that operates Power dissipation from a single 5 V power supply, VDD. It contains a low power, 3.3 mW at 5 V/100 kSPS high speed, 14-bit sampling ADC with no missing codes, an 3.3 W at 5 V/100 SPS internal conversion clock, and a versatile serial interface port. Standby current: 1 nA The part also contains a low noise, wide bandwidth, short 10-lead MSOP (MSOP-8 size) and aperture delay track-and-hold circuit. On the CNV rising edge, 3 mm 3 mm LFCSP (SOT-23 size) it samples an analog input IN+ between 0 V to REF with respect Pin-for-pin compatible with the 16-bit AD7686 to a ground sense IN. The reference voltage, REF, is applied externally and can be set up to the supply voltage. APPLICATIONS Its power scales linearly with throughput. Battery-powered equipment Data acquisition The SPI-compatible serial interface also features the ability, Instrumentation using the SDI input, to daisy-chain several ADCs on a single, Medical instruments 3-wire bus, or it provides an optional BUSY indicator. It is Process control compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate supply VIO. The AD7946 is housed in a 10-lead MSOP or a 10-lead LFCSP with operation specified from 40C to +85C. 1 Protected by U.S. Patent 6,703,961. Table 1. MSOP, LFCSP 14-/16-/18-Bit PulSAR ADC Type 100 kSPS 250 kSPS 400 kSPS to 500 kSPS 1000 kSPS ADC Driver 1 1 14-Bit AD7940 AD7942 AD7946 1 1 1 16-Bit AD7680 AD7685 AD7686 AD7980 ADA4941 1 1 1 AD7683 AD7687 AD7688 AD7983 ADA4841 1 AD7684 AD7694 AD7693 1 1 1 18-Bit AD7691 AD7690 AD7982 ADA4941 1 AD7984 ADA4841 1 Pin-for-pin compatible. Rev. B 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. 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Technical Support www.analog.com 04656-001AD7946 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Voltage Reference Input ............................................................ 14 Applications ....................................................................................... 1 Power Supply ............................................................................... 15 Typical Application Circuit ............................................................. 1 Supplying the ADC from the Reference .................................. 15 General Description ......................................................................... 1 Single-Supply Application ......................................................... 15 Revision History ............................................................................... 2 Digital Interface .......................................................................... 16 Specifications ..................................................................................... 3 CS MODE 3-Wire, No BUSY Indicator .................................. 17 Timing Specifications .................................................................. 5 CS Mode 3-Wire with BUSY Indicator ................................... 18 Absolute Maximum Ratings ............................................................ 6 CS Mode 4-Wire, No BUSY Indicator ..................................... 19 ESD Caution .................................................................................. 6 CS Mode 4-Wire with BUSY Indicator ................................... 20 Pin Configurations and Function Descriptions ........................... 7 Chain Mode, No BUSY Indicator ............................................ 21 Typical Performance Characteristics ............................................. 8 Chain Mode with BUSY Indicator ........................................... 22 Terminology .................................................................................... 11 Application Guidelines .................................................................. 23 Theory of Operation ...................................................................... 12 Layout .......................................................................................... 23 Circuit Information .................................................................... 12 Evaluating the Performance of the AD7946 .............................. 23 Converter Operation .................................................................. 12 Outline Dimensions ....................................................................... 24 Typical Connection Diagram.................................................... 13 Ordering Guide .......................................................................... 24 Analog Input ............................................................................... 13 Driver Amplifier Choice ............................................................ 14 REVISION HISTORY 7/14Rev. A to Rev. B 12/07Rev. 0 to Rev. A Replaced QFN with LFCSP .......................................... Throughout QFN Package Available ...................................................... Universal Changed Application Diagram Section to Typical Application Changes to Table 1 ............................................................................. 1 Circuit Section .................................................................................. 1 Changes to Table 5 ............................................................................. 6 Changes to Product Title and Features Section ............................ 1 Changes to Ordering Guide .......................................................... 24 Added Note 1, General Description Section ................................. 1 7/05Revision 0: Initial Version Added EPAD Notation to Figure 5 and Table 6............................ 7 Changes to Figure 25 ...................................................................... 13 Changes to Evaluating the Performance of the AD7946 Section ... 23 Updated Outline Dimensions ....................................................... 24 Changes to Ordering Guide .......................................................... 24 Rev. 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