Low Power, 24-Bit, 31.25 kSPS, Sigma-Delta ADC with True Rail-to-Rail Buffers Data Sheet AD7172-4 FEATURES GENERAL DESCRIPTION Fast and flexible output rate: 1.25 SPS to 31.25 kSPS The AD7172-4 is a low noise, low power, multiplexed, - analog- Channel scan data rate of 6.21 kSPS/channel (161 s settling) to-digital converter (ADC) with 4- or 8-channel (fully differential/ Performance specifications single-ended) inputs for low bandwidth signals. The AD7172-4 17.2 noise free bits at 31.25 kSPS has a maximum channel scan rate of 6.21 kSPS (161 s) for fully 24 noise free bits at 5 SPS settled data. The output data rates range from 1.25 SPS to 31.25 kSPS. INL: 2 ppm of FSR The AD7172-4 integrates key analog and digital signal condition- 85 dB rejection of 50 Hz and 60 Hz with 50 ms settling ing blocks to allow users to configure an individual setup for User configurable input channels each analog input channel in use via the SPI. Integrated true rail-to- 4 fully differential channels or 8 single-ended channels rail buffers on the analog inputs and reference inputs provide easy Crosspoint multiplexer to drive high impedance inputs. True rail-to-rail analog and reference input buffers The digital filter allows simultaneous 50 Hz and 60 Hz rejection Internal or external clock at a 27.27 SPS output data rate. The user can switch between Power supply different filter options according to the demands of each channel AVDD1 = 3.0 V to 5.5 V, AVDD2 = IOVDD = 2 V to 5.5 V in the application, with further digital processing functions such Split supply with AVDD1 and AVSS at 2.5 V or 1.65 V as offset and gain calibration registers, which are configurable ADC current: 1.5 mA on a per channel basis. General-purpose input/outputs (GPIOs) Temperature range: 40C to +105C control external multiplexers synchronous to the ADC conversion 3- or 4-wire serial digital interface (Schmitt trigger on SCLK) timing. The specified temperature range is 40C to +105C. Serial port interface (SPI), QSPI-, MICROWIRE-, and DSP- The AD7172-4 is in a 5 mm 5 mm, 32-lead LFCSP. compatible Note that, throughout this data sheet, the dual function pin APPLICATIONS names are referenced by the relevant function only. Process control: PLC/DCS modules Temperature and pressure measurement Medical and scientific multichannel instrumentation Chromatography FUNCTIONAL BLOCK DIAGRAM AVDD1 AVDD2 REGCAPA REF REF+ IOVDD REGCAPD CROSSPOINT 1.8V 1.8V MULTIPLEXER RAIL-TO-RAIL LDO LDO REFERENCE INPUT BUFFERS RAIL-TO-RAIL AIN0/REF2 ANALOG AVDD CS INPUT BUFFERS SCLK AIN1/REF2+ SERIAL DIN DIGITAL INTERFACE - ADC FILTER AND CONTROL DOUT/RDY SYNC AIN7 ERROR XTAL AND INTERNAL I/O AND EXTERNAL AVSS CLOCK OSCILLATOR AIN8 MUX CONTROL CIRCUITRY AD7172-4 AVSS PDSW GPIO0 GPIO1 GPO2 GPO3 XTAL1 XTAL2/CLKIO DGND Figure 1. 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. No Tel: 781.329.4700 20152017 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. 12676-001AD7172-4 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 CRC Calculation ......................................................................... 40 Applications ....................................................................................... 1 Integrated Functions ...................................................................... 42 General Description ......................................................................... 1 General-Purpose Input/Output................................................ 42 Functional Block Diagram .............................................................. 1 External Multiplexer Control ................................................... 42 Revision History ............................................................................... 3 Delay ............................................................................................ 42 Specif icat ions ..................................................................................... 4 16-Bit/24-Bit Conversions ......................................................... 42 Timing Characteristics ................................................................ 7 DOUT RESET ........................................................................... 42 Timing Diagrams .......................................................................... 7 Synchronization .......................................................................... 42 Absolute Maximum Ratings ............................................................ 8 Error Flags ................................................................................... 43 Thermal Resistance ...................................................................... 8 DATA STAT ............................................................................... 43 ESD Caution .................................................................................. 8 IOSTRENGTH ........................................................................... 43 Pin Configuration and Function Descriptions ............................. 9 Grounding and Layout .................................................................. 44 Typical Performance Characteristics ........................................... 11 Register Summary .......................................................................... 45 Noise Performance and Resolution .............................................. 17 Register Details ............................................................................... 47 Getting Started ................................................................................ 18 Communications Register ......................................................... 47 Power Supplies ............................................................................ 19 Status Register ............................................................................. 48 Digital Communication ............................................................. 19 ADC Mode Register ................................................................... 49 AD7172-4 Reset .......................................................................... 20 Interface Mode Register ............................................................ 50 Configuration Overview ........................................................... 20 Register Check ............................................................................ 51 Circuit Description ......................................................................... 26 Data Register ............................................................................... 51 Buffered Analog Input ............................................................... 26 GPIO Configuration Register ................................................... 52 Crosspoint Multiplexer .............................................................. 26 ID Register................................................................................... 53 AD7172-4 Reference .................................................................. 27 Channel Register 0 ..................................................................... 54 Buffered Reference Input ........................................................... 28 Channel Register 1 to Channel Register 7 .............................. 55 Clock Source ............................................................................... 28 Setup Configuration Register 0 ................................................ 56 Digital Filters ................................................................................... 29 Setup Configuration Register 1 to Setup Configuration Register 7 ..................................................................................... 57 Sinc5 + Sinc1 Filter ..................................................................... 29 Filter Configuration Register 0 ................................................. 58 Sinc3 Filter ................................................................................... 29 Filter Configuration Register 1 to Filter Configuration Single Cycle Settling ................................................................... 30 Register 7 ..................................................................................... 59 Enhanced 50 Hz and 60 Hz Rejection Filters ......................... 33 Offset Register 0 ......................................................................... 59 Operating Modes ............................................................................ 35 Offset Register 1 to Offset Register 7 ....................................... 59 Continuous Conversion Mode ................................................. 35 Gain Register 0............................................................................ 60 Continuous Read Mode ............................................................. 36 Gain Register 1 to Gain Register 7 ........................................... 60 Single Conversion Mode ........................................................... 37 Outline Dimensions ....................................................................... 61 Standby and Power-Down Modes ............................................ 38 Ordering Guide .......................................................................... 61 Calibration ................................................................................... 38 Digital Interface .............................................................................. 39 Checksum Protection ................................................................. 39 Rev. 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