系统板 5883

MAXREFDES32#:带反激直流电源的双通道模拟输入/模拟输出



MAXREFDES32#系统板 MAXREFDES32#系统板 放大+

概述

高级制造、定制生产和成本压力持续推动工厂向更高速性能和更高灵活性方向发展。为满足“不妥协”工厂环境的要求,MAXREFDES32#子系统参考设计提供两路高速、高精度、400ksps、16位模拟输入通道和输出通道。所有输入和输出通道支持±10V和±20mA信号,外加20%裕量,为使用电压或电流信号的低、高速系统提供了灵活性。

MAXREFDES32#设计使用四片双通道快速稳定高压运算放大器(MAX9633);两片16位500ksps ADC (MAX11166);两片低噪声、快速稳定、高精度、16位DAC (MAX5316);两片超高精度4.096V电压基准(MAX6126);七片高速数字隔离器(MAX14850);支持反激/Boost电源的峰值电流模式转换器(MAX17498B);以及+18V、-18V、+5V和-1.25V线性稳压电源(MAX8719、MAX8881)。通过使用高精度和高速元件,子系统在过程控制应用(例如传感器输入)和控制应用(例如伺服驱动、分解器和编码器)领域都表现良好。

MAXREFDES32子系统设计方框图
图1. MAXREFDES32子系统设计方框图。

特性

  • 两路独立模拟输入
  • 两路独立模拟输出
  • 隔离电源和数据
  • 高速400ksps模拟输入采样率
  • 高精度16位分辨率
  • 电压输出在17µs内稳定到2 LSB之内
  • 电压输出在77µs内稳定到2 LSB之内
  • 器件驱动器
  • C语言源代码示例
  • ZedBoard™平台配置文件
  • 兼容FMC

竞争优势

  • 高速
  • 高精度
  • 低噪声

应用

  • 工业控制自动化
  • 伺服驱动
MAXREFDES32# System Board 放大+

Introduction

Advanced manufacturing, custom production and cost pressures continue to drive factories to higher speed performance and increased flexibility. To meet the requirements of a ‘no compromises’ factory environment, the MAXREFDES32# subsystem reference design provides two high-speed, high-accuracy, 400ksps, 16-bit analog input channels and output channels. All input and output channels support ±10V and ±20mA signals plus 20% margin, providing flexibility for low- and high-speed systems using either voltage or current signals.

The MAXREFDES32# design utilizes four dual fast-settling high-voltage op amps (MAX9633); two 16-bit 500ksps ADCs (MAX11166); two low-noise, fast-settling precision 16-bit DACs (MAX5316); two ultra-high precision 4.096V voltage references (MAX6126); seven high-speed digital isolators (MAX14850); a peak-current-mode converter for flyback/boost supplies (MAX17498B); and regulated +18V, -18V, +5V, and -1.25V power rails (MAX8719, MAX8881). By using high-accuracy and high-speed components, this subsystem performs well in both process control applications, such as sensor inputs, and control applications, such as servo drives, resolvers, and encoders.

The MAXREFDES32 subsystem design block diagram.
Figure 1. The MAXREFDES32 subsystem design block diagram.

Features

  • Two independent analog inputs
  • Two independent analog outputs
  • Isolated power and data
  • High-speed 400ksps analog input sampling rate
  • High-accuracy 16-bit resolution
  • Voltage output settles to within 2 LSB in 17µs
  • Current output settles to within 2 LSB in 77µs
  • Device drivers
  • Example C source code
  • Configuration files for ZedBoard™ platform
  • FMC-compatible

Competitive Advantages

  • High speed
  • High accuracy
  • Low noise

Applications

  • Industrial control automation
  • Servo drive

Detailed Description of Hardware

The MAXREFDES32# subsystem is optimized for applications that need both analog inputs and analog outputs with isolated power and data. Figure 1 shows the block diagram of the MAXREFDES32# reference design.

MAXREFDES32# uses an external MAX6126 (U12 and U22) voltage reference for both the ADC and the DAC to provide the highest possible accuracy. The MAX6126 has an initial accuracy of 0.02% and a 3ppm/ºC maximum temperature coefficient (tempco).

The MAX9633 (U1) is a dual high-voltage, low-noise op amp. The op amps attenuate and buffer the input signals to match the input range of the ADC (MAX11166). When measuring a voltage signal, connect the positive terminal and negative terminal of the signal source to the Vx+/Ix+ and Vx-/Ix- connectors, respectively. When measuring a current signal, connect the positive terminal of the signal source to the Vx+/Ix+ connector, and connect the negative terminal to both Vx-/Ix- and Ix- connectors. The input buffer is configured in a difference amplifier configuration. The equation to convert the ADC code to input voltage is:

V = 3.6621 × 10-4 × (CODEADC - 32768)

When measuring the current signal, if the Ix- terminal is connected to the ground of the current loop, the equation to convert the ADC code to current is:

I = 7.4466 × 10-7 × (CODEADC - 32768)

The MAX5316 (U17 and U18) is a low-noise, fast-settling, 16-bit DAC. The range of the DAC outputs is 0V to 4.096V. The dual op amp, MAX9633 (U19), buffers the DAC outputs and rescales the output range to -10V to +10V (±2V) to meet the industrial standard. A second dual op amp, MAX9633 (U20), buffers the outputs of the first MAX9633 (U19). A third dual op amp, MAX9633 (U21), uses the Howland current source configuration to convert the voltage output of the second MAX9633 (U20) into -20mA to +20mA (±4mA) current output. Therefore, the MAXREFDES32# can produce two channels of both voltage and current outputs simultaneously. The equations to convert the DAC code to output voltage and current are:

V = 3.6758 × 10-4 × CODEDAC - 12.0055

I = 7.3517 × 10-7 × CODEDAC - 2.4011 × 10-2

In standard configuration, the MAXREFDES32# uses the MAX17498B (U23) to generate the isolated +22V, -22V, +7V, and -7V rails from a 24V supply. The MAX8719 (U4), MAX8881 (U5, U6), and LM337 (U7, U8) provide post-regulated +18V, +5V, -18V, and -1.25V rails. Data isolation is accomplished using the MAX14850 (U9–U11, U13–U16) digital data isolators. The combined power and data isolation achieved is 600VRMS. To use external power supplies, disconnect the 24V supply and move the shunts on all jumpers to the 2-3 position. Connect the ground terminal of the external power supplies to the GND connector. Connect the +18V, +5V, -1.25V, and -18V supplies to the corresponding connectors on the board.

MAXREFDES32# connects to FMC-compatible field-programmable gate array (FPGA)/microcontroller development boards. MAXREFDES32# requires a 24V supply and also the 3.3V supply from the FMC connector. The FMC pin assignments are illustrated in Figure 2.

FMC connector pin connections.
Figure 2. FMC connector pin connections.

Table 1 shows the power requirements. Table 2 shows currently supported platforms and ports.

Table 1. Power Requirement for the MAXREFDES32# Subsystem Reference Design

Power Type Jumper Shunt Input Voltage (V) Input Current (mA, typ)
MAX17498B Powered JU1–JU5: 1-2 24 125
External Power JU1–JU5: 2-3 5 88.8
18 26.8
-18 37.4
-1.25 1.8

 

Table 2. Supported Platforms and Ports

Supported Platforms Ports
ZedBoard platform (Zynq®-7020) J1

Detailed Description of ZedBoard Firmware

Table 2 shows the currently supported platforms and ports. Support for additional platforms may be added periodically under Firmware Files in the All Design Files section.

The MAXREFDES32# firmware released for the ZedBoard kit targets an ARM® Cortex®-A9 processor placed inside a Xilinx® Zynq system-on-chip (SoC).

The firmware is a working example of how to interface to the hardware, collect samples, save them to memory, and replicate the input signals on the outputs. Figure 3 shows the process flow. The firmware is written in C using the Xilinx SDK tool, which is based on the Eclipse open source standard. Custom MAXREFDES32# design functions were created utilizing the AXI MAXREFDES32 custom IP core. The firmware supports the maximum ADC sampling rate at 400ksps. The maximum signal replication rate is 60ksps because the settling time for the voltage output signals is 17µs. Because the settling time for current output signals is 77µs, a replication rate of 10ksps or less is recommended.


Figure 3. The MAXREFDES32# firmware flowchart.

The firmware accepts commands, configures the ADC and DAC, replicates the inputs on outputs, and is capable of downloading blocks of sampled data to a standard terminal program through a virtual COM port. The complete source code is provided to speed up customer development. The corresponding firmware platform files contain code documentation.

Quick Start

Required Equipment:

  • Windows® PC with two USB ports
  • MAXREFDES32# (MAXREFDES32#) board
  • MAXREFDES32#-supported platform (i.e., ZedBoard kit)
  • Industrial signal source

Download, read, and carefully follow each step in the appropriate MAXREFDES32# Quick Start Guide: MAXREFDES32# ZedBoard Quick Start Guide

Lab Measurements

Equipment used for analog input tests:

  • Audio Precision® SYS-2722 signal source or equivalent
  • Voltage calibrator DVC-8500
  • Windows PC with two USB ports
  • MAXREFDES32# board
  • ZedBoard kit

Equipment used for analog output tests:

  • Maxim custom FPGA test board
  • One 499Ω, 0.25W resistor load
  • Agilent 3458A digital multimeter
  • Agilent E3631A DC power supply (any ±24V, 25mA minimum DC power supply works)
  • National Instruments GPIB card and cable
  • Perl script for controlling the FPGA development kit and measurement equipment
  • Windows PC

Take special care and use proper equipment when testing the MAXREFDES32# design. Duplication of the presented test data requires a signal source with higher accuracy than the design being tested. A low distortion signal source is absolutely required to duplicate the presented results. The input signal was generated using the Audio Precision SYS-2722. The FFTs were created using the FFT control in SignalLab from Mitov Software.


Figure 4. AC FFT for channel 1 (AIN1) using on-board power, a differential -12V to +12V, 20kHz sine wave input signal, a 400ksps sample rate, and a Blackman-Harris window at room temperature.


Figure 5. DC histogram for channel 1 (AIN1) using on-board pwer; a 0V DC input signal; a 400ksps sample rate; 65,536 samples; a code spread of 6 LSBs with 99.9% of the codes falling within the four center LSBs; and a standard deviation of 0.625 at room temperature.


Figure 6. INL for -10V to +10V output range, with 20% overrange.


Figure 7. DNL for -10V to +10V output range, with 20% overrange.


Figure 8. Output error for -10V to +10V output range, with 20% overrange.


Figure 9. INL for -20mA to +20mA output range, with 20% overrange.


Figure 10. DNL for -20mA to +20mA output range, with 20% overrange.


Figure 11. Output error for -20mA to +20mA output range, with 20% overrange.

ARM is a registered trademark and registered service mark of ARM Limited.
Audio Precision is a registered trademark of Audio Precision, Inc.
Cortex is a registered trademark of ARM Limited.
Eclipse is a trademark of Eclipse Foundation, Inc.
Windows is a registered trademark and registered service mark of Microsoft Corporation.
Xilinx is a registered trademark and registered service mark of Xilinx, Inc.
ZedBoard is a trademark of ZedBoard.org
Zynq is a registered trademark of Xilinx, Inc.

Quick Start

Required Equipment:

  • Windows® PC with two USB ports
  • MAXREFDES32# (MAXREFDES32#) board
  • MAXREFDES32#-supported platform (i.e., ZedBoard kit)
  • Industrial signal source

Download, read, and carefully follow each step in the appropriate MAXREFDES32# Quick Start Guide: MAXREFDES32# ZedBoard Quick Start Guide

 
Status:
Package:
Temperature:

MAX11166
16位、500ksps、内置基准的±5V SAR ADC,TDFN封装

  • 高直流/交流精度提高测量质量
  • 高度集成的ADC节省成本和空间
  • 较宽电源范围和低功耗,简化电源设计

MAX14850
六通道数字隔离器

  • 高压保护
  • 完整的数字隔离方案
  • 兼容多种接口标准

MAX5316
16位、±1 LSB高精度电压输出DAC,SPI接口

  • 理想用于ATE和高精度设备
  • 驱动10kΩ || 100pF负载时可快速建立(3µs)
  • 上电时,将DAC输出安全地复位至零或中间值(引脚可选)

MAX17498B
AC-DC和DC-DC峰值电流模式转换器,支持反激/Boost应用

  • 峰值电流模式反激/boost转换器
  • 电流模式控制提供极佳的瞬态响应
  • 固定开关频率

MAX9633
双通道36V运算放大器,用于18位SAR ADC前端

  • 低噪声(1kHz时为3nV/)和低失真(10kHz时为130dB) ADC驱动器
  • 750ns快速建立时间,16位精度
  • 200µV (最大值)低输入失调电压

MAX8719
高压、低功耗线性稳压器,用于笔记本电脑

  • 4V至28V输入范围
  • 18µA静态电源电流
  • <3µA关断电源电流

  • MAX6126
    超高精度、超低噪声、串联型电压基准

    • 1.3µVP-P超低噪声(0.1Hz至10Hz,2.048V输出)
    • 3ppm/°C (最大值)超低温度系数
    • ±0.02% (最大值)初始精度

    MAX8881
    12V、超低IQ、低压差线性稳压器,带有POK

    • 电源电流:3.5µA @ 12V
    • 电池反接保护
    • 2.5V至12V输入电压范围
    类型 编号 PDF 标题
    用户手册 5885 MAXREFDES32# ZedBoard Quick Start Guide