AD4111低功耗低噪音24位Σ－ΔADC解决方案

电子工程师 2019-05-01 6191

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描述

　　ADI公司的AD4111是具有±10V和0 mA至20 mA输入和明线检测功能的低功耗 24 位 Σ-Δ ADC，集成了模拟前端（AFE），还集成主要模拟和数字的信号调理区快，为每个模拟输入通路配置成八种单独建立图，最大通路扫描速率6.2 kSPS（161 μs），嵌入的2.5V低漂移（5 ppm/℃）能隙基准电压降低了外接元件数量，单电源5V或3.3V工作，工作温度−40℃ 到 +105℃，主要用在过程控制PLC和DCS模块。本文介绍了AD4111主要特性，功能框图以及评估板EVAL-AD4111SDZ主要特性，框图，电路图，材料清单和PCB设计图。

　　The AD4111 is a low power， low noise， 24-bit， sigma-delta （Σ-Δ） analog-to-digital converter （ADC） that integrates an analog front end （AFE） for fully differential or single-ended， high impedance（≥1 MΩ） bipolar，±10 V voltage inputs， and 0 mA to 20 mA current inputs. The AD4111 also integrates key analog and digital signalconditioning blocks to configure eight individual setups for each analog input channel in use. The AD4111 features amaximum channel scan rate of 6.2 kSPS （161 μs） for fullysettled data.

　　The embedded 2.5 V， low drift （5 ppm/℃）， band gap internal reference （with output reference buffer） reduces the external component count. The digital filter allows flexible settings， including simultaneous50 Hz and 60 Hz rejection at a 27.27 SPS output data rate. The user can select between the different filter settings depending on the demands of each channel in the application. The automatic channel sequencer enables the ADC to switch through eachenabled channel.

　　The precision performance of the AD4111 is achieved by integrating the proprietary iPassives™ technology from Analog Devices， Inc. The AD4111 is factory calibrated to achieve a high degree of specified accuracy.

　　The AD4111 also has the unique feature of open wire detection on the voltage inputs （patent pending） for system level diagnosticsusing a single 5 V or 3.3 V power supply. The AD4111 operates with a single power supply， making it easy to use in galvanically isolated applications. The specified operating temperature range is −40℃ to +105℃。 The AD4111 is housedin a 40-lead， 6 mm × 6 mm LFCSP package.

　　AD4111主要特性：

　　24-bit ADC with integrated analog front end

　　Up to 6.2 kSPS per channel （161 μs per channel）

　　16 noise free bits at 1 kSPS per channel

　　85 dB rejection of 50 Hz and 60 Hz at 20 SPS per channel

　　±10 V inputs， 4 differential or 8 single-ended Overrange up to ±20 V ≥1 MΩ impedance

　　±0.06% accuracy at 25℃ Open wire detection 0 mA to 20 mA inputs，4 single-ended Overrange from −0.5 mA to +24 mA

　　60 Ω impedance

　　±0.08% accuracy at 25℃ On-chip 2.5 V reference ±0.12% accuracy at 25℃

　　， ±5 ppm/℃ （typical） drift Internal or external clock

　　Power supplies

　　AVDD = 3.0 V to 5.5 V

　　IOVDD = 2 V to 5.5 V

　　Total IDD = 3.9 mA

　　Temperature range： −40℃ to +105℃ 3-wire or 4-wire serial digital interface （Schmitt trigger on SCLK）

　　SPI， QSPI， MICROWIRE， and DSP compatible

　　AD4111应用：

　　Process control PLC and DCS modules

　　图1.AD4111功能框图

　　评估板EVAL-AD4111SDZ

　　Evaluating the AD4111 ±10 V and 0 mA to 20 mA， Analog Front End forIndustrial Automation Systems

　　The EVAL-AD4111SDZ evaluation kit features the AD4111，a 24-bit， 31.25 kSPS analog-to-digital converter （ADC） with a±10 V input voltage range （4 single-ended or 8 differentialchannels） with open wire detection and 4 current channelsoperating from 0 mA to 20 mA. All channels have on-board overvoltage and overcurrent protection. The EVAL-AD4111SDZ board includes voltage reference， power， and data insulation and can be connected to the Analog Devices， Inc.， SDP-B system demonstration platform （EVAL-

　　SDP-CB1Z）。 The SDP-B board provides connection to a PC viaUSB port and can provide power for the EVAL-AD4111SDZboard from the PC USB port.

　　The AD411X Eval+ evaluation software configures the AD4111device functionality and provides open wire detection， dc timedomain analysis in the form of waveform graphs， histograms，and associated noise analysis for ADC performance evaluation.

　　Full specifications for the AD4111 are available in the productdata sheet， which must be consulted in conjunction with thisuser guide when working with this evaluation board.

　　评估板EVAL-AD4111SDZ主要特性：

　　Fully featured evaluation board for the AD4111

　　PC control in conjunction with Analog Devices， Inc.， SDP-B

　　system demonstration platform （EVAL-SDP-CB1Z）

　　PC software for control and data analysis （time domain）

　　评估板EVAL-AD4111SDZ包括：

　　EVAL-AD4111SDZ evaluation board

　　Required software： AD411X Eval+

　　图2.评估板EVAL-AD4111SDZ外形图