Analog Devices: CN0194 Reference Design for Galvanically Isolated, 2-Channel, 16-Bit, Simultaneous Sampling, Daisy-Chained Data Acquisition System

atomar — Sun, 27 Oct 2013 06:01:51 GMT

Current Revision posted to Documents by atomar on 10/27/2013 6:01:51 AM

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Kit Overview

This circuit provides galvanic isolation for high speed, high accuracy, simultaneous sampling analog-todigital conversion applications. The 16-bit AD7685AD7685 PulSAR ADC is versatile and allows monitoring of multiple channels through daisy chaining. An input circuit based on the AD8615AD8615 op amp level shifts, attenuates, and buffers a ±10 V industrial signal to match the input requirements of the ADC. The flexible circuit includes a precision ADR391ADR391 reference and two quadchannel ADuM1402 digital isolators to provide a compact and cost effective solution to a popular industrial data acquisition application.

The AD7685AD7685 is a 16-bit, charge redistribution successive approximation (SAR) analog-to-digital converter (ADC) that operates from a single VDD power supply from 2.3 V to 5.5 V. It contains a low power, high speed, 16-bit sampling ADC with no missing codes, no pipeline delay, an internal conversion clock, and a versatile serial interface port. The ADC also contains a low noise, wide bandwidth, short aperture delay, track-and-hold circuit.

The complete analog signal chain runs on a single 5 V supply. The ADR391BUJZ-R2ADR391BUJZ-R2 low dropout 2.5 V reference and the U13 rail-torail CMOS AD8615 op amp develop the 4.5 V reference voltage for the ADCs.

This circuit uses the EVAL-CN0194-SDPZEVAL-CN0194-SDPZ circuit board and the EVAL-SDP-CB1ZEVAL-SDP-CB1Z System Demonstration Platform (SDP-B) evaluation board. The two boards have 120-pin mating connectors, allowing for the quick setup and evaluation of the circuit’s performance. The EVAL-CN0194-SDPZ board contains the circuit to be evaluated and the SDP evaluation board is used with the CN0194 evaluation software to capture the data from the EVAL-CN0194-SDPZ circuit board.

Key Applications: Electronic Test & Measurement, Programmable Logic Controllers/ Distributed Control Systems

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Development Tools

PC with a USB port and Windows® XP, Windows Vista (32-bit), or Windows 7 (32-bit)
EVAL-CN0194-SDPZEVAL-CN0194-SDPZ circuit evaluation board
EVAL-SDP-CB1ZEVAL-SDP-CB1Z SDP evaluation board
- Blackfin Processor ADSP-BF527
- USB 2.0 Interface to PC
- JTAG header footprint
- 32MB SDRAM
- 2 x Small Footprint 120 Pin Connectors
- Configurable Peripheral Interfaces - SPI - SPORT - I2C - GPIOs - Parallel - Timers
CN-0194 evaluation software
Power supply: +6 V, or +6 V “wall wart” (EVAL-CFTL-6V-PWRZEVAL-CFTL-6V-PWRZ)
Low distortion signal source, such as Audio Precision System Two 2322

Technical Documents

Learning Center

Type	Description
User Manual	ADI: User Manual for CN-0194 Galvanically Isolated, 2-Channel, 16-Bit, Simultaneous Sampling, Daisy-Chained Data Acquisition System
User Guide	ADI: User Guide for EVAL-SDP-CB1Z
User Guide	ADI: Getting Started with SDP
Datasheet	ADI: Datasheet for AD7685: 16-Bit, 250 kSPS PulSAR ADC in MSOP/QFN (Rev C)
Datasheet	ADI: Datasheet for AD8615/AD8618: Precision, 20 MHz, CMOS, Rail-to-Rail Input/Output Operational Amplifiers Data Sheet (Rev E)
Datasheet	ADI: Datasheet for ADR391/ADR392/ADR395: Micropower, Low Noise Precision Voltage References with Shutdown (Rev H)
Datasheet	ADI: Datasheet for ADuM1400/ADuM1401/ADuM1402: Quad-Channel Digital Isolators (Rev H)

Design Elements

Type	Description
Schematics	ADI: Schematics for EVAL-CN0194-SDPZ Evaluation Board
Layout	ADI: Layout for EVAL-CN0194-SDPZ
BOM	ADI: Bill of Material (BOM) for EVAL-CN0194-SDPZ Evaluation Board
Reference Design	ADI: Reference Design for CN0194 FMC-SDP Interposer & Evaluation Board / Xilinx KC705

Video

Video 1	Video 2
www.youtube.com/watch	www.youtube.com/watch

Kit Features

Key Features for EVAL-CN0194-SDPZEVAL-CN0194-SDPZ Evaluation Board are as below:

Provides galvanic isolation for high speed, high accuracy, simultaneous sampling analog-to-digital conversion applications
The 16-bit AD7685 PulSAR ADC is versatile and allows monitoring of multiple channels through daisy chaining
- Features for AD7685AD7685:
- 16-bit resolution with no missing codes
- Throughput: 250 kSPS
- INL: ±0.6 LSB typical, ±2 LSB maximum (±0.003% of FSR)
- SINAD: 93.5 dB @ 20 kHz
- THD: −110 dB @ 20 kHz
- Pseudo differential analog input range 0 V to VREF with VREF up to VDD
- No pipeline delay
- Single-supply operation 2.3 V to 5.5 V with 1.8 V to 5 V logic interface
- Serial interface SPI®-/QSPI™-/MICROWIRE™-/DSP-compatible
- Daisy-chain multiple ADCs, BUSY indicator
- Power dissipation: 1.4 μW @ 2.5 V/100 SPS, 1.35 mW @ 2.5 V/100 kSPS, 4 mW @ 5 V/100 kSPS
- Standby current: 1 nA
An input circuit based on the AD8615AD8615 op-amp level shifts, attenuates, and buffers a ±10 V industrial signal to match the input requirements of the ADC
The flexible circuit includes a precision ADR391ADR391 reference and two quadchannel ADuM1402 digital isolators to provide a compact and cost effective solution to a popular industrial data acquisition application

Kit Contents

The Analog Devices EVAL-CN0194-SDPZEVAL-CN0194-SDPZ kit is supplied with below contents:

Evaluation Board

Tags: adr391, ad7685, eval-cn0194-sdpz, ad8615, analog_devices