14-Bit, 8-Channel, 250 kSPS PulSAR ADC Data Sheet AD7949 FEATURES FUNCTIONAL BLOCK DIAGRAM 2.3V TO 5.5V 0.5V TO VDD 0.5V 0.5V TO VDD 14-bit resolution with no missing codes 0.1F 10F 8-channel multiplexer with choice of inputs REFIN REF VDD Unipolar single-ended Differential (GND sense) 1.8V BAND GAP VIO TO Pseudobipolar REF AD7949 VDD Throughput: 250 kSPS TEMP SENSOR INL/DNL: 0.5/0.25 LSB typical CNV IN0 SINAD: 85 dB 20 kHz IN1 SCK IN2 14-BIT SAR SPI SERIAL MUX THD: 100 dB 20 kHz IN3 INTERFACE ADC SDO IN4 Analog input range: 0 V to V with V up to VDD REF REF ONE-POLE DIN IN5 LPF Multiple reference types IN6 SEQUENCER IN7 Internal selectable 2.5 V or 4.096 V COM External buffered (up to 4.096 V) GND External (up to VDD) Internal temperature sensor (TEMP) Figure 1. Channel sequencer, selectable 1-pole filter, busy indicator Table 1. Multichannel 14-/16-Bit PulSAR ADCs No pipeline delay, SAR architecture Type Channels 250 kSPS 500 kSPS ADC Driver Single-supply 2.3 V to 5.5 V operation with 14-Bit 8 AD7949 ADA4841-1 1.8 V to 5.5 V logic interface 16-Bit 4 AD7682 ADA4841-1 Serial interface compatible with SPI, MICROWIRE, 16-Bit 8 AD7689 AD7699 ADA4841-1 QSPI, and DSP Power dissipation 2.9 mW 2.5 V/200 kSPS GENERAL DESCRIPTION 10.8 mW 5 V/250 kSPS The AD7949 is an 8-channel, 14-bit, charge redistribution Standby current: 50 nA successive approximation register (SAR) analog-to-digital 20-lead 4 mm 4 mm LFCSP package converter (ADC) that operates from a single power supply, VDD. APPLICATIONS The AD7949 contains all components for use in a multichannel, low power data acquisition system, including a true 14-bit SAR Multichannel system monitoring ADC with no missing codes an 8-channel, low crosstalk Battery-powered equipment Medical instruments: ECG/EKG multiplexer that is useful for configuring the inputs as single- Mobile communications: GPS ended (with or without ground sense), differential, or bipolar Power line monitoring an internal low drift reference (selectable 2.5 V or 4.096 V) and Data acquisition buffer a temperature sensor a selectable one-pole filter and a Seismic data acquisition systems sequencer that is useful when channels are continuously Instrumentation scanned in order. Process control The AD7949 uses a simple SPI interface for writing to the configuration register and receiving conversion results. The SPI interface uses a separate supply, VIO, which is set to the host logic level. Power dissipation scales with throughput. The AD7949 is housed in a tiny 20-lead LFCSP with operation specified from 40C to +85C. Rev. F 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 20082017 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 07351-001AD7949 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Voltage Reference Output/Input .............................................. 19 Applications ....................................................................................... 1 Power Supply ............................................................................... 21 Functional Block Diagram .............................................................. 1 Supplying the ADC from the Reference .................................. 21 General Description ......................................................................... 1 Digital Interface .............................................................................. 22 Revision History ............................................................................... 3 Reading/Writing During Conversion, Fast Hosts .................. 22 Specifications ..................................................................................... 4 Reading/Writing After Conversion, Any Speed Hosts .......... 22 Timing Specifications .................................................................. 6 Reading/Writing Spanning Conversion, Any Speed Host .... 23 Absolute Maximum Ratings ............................................................ 8 Configuration Register, CFG .................................................... 23 ESD Caution .................................................................................. 8 General Timing Without a Busy Indicator ............................. 25 Pin Configuration and Function Descriptions ............................. 9 General Timing with a Busy Indicator .................................... 26 Typical Performance Characteristics ........................................... 10 Channel Sequencer .................................................................... 27 Terminology .................................................................................... 13 Read/Write Spanning Conversion Without a Busy Indicator ....................................................................................................... 28 Theory of Operation ...................................................................... 14 Read/Write Spanning Conversion with a Busy Indicator ..... 30 Overview ...................................................................................... 14 Application Hints ........................................................................... 31 Converter Operation .................................................................. 14 Layout .......................................................................................... 31 Transfer Functions...................................................................... 15 Evaluating AD7949 Performance ............................................. 31 Typical Connection Diagrams .................................................. 16 Outline Dimensions ....................................................................... 32 Analog Inputs .............................................................................. 17 Ordering Guide .......................................................................... 32 Driver Amplifier Choice ............................................................ 19 Rev. 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