1、以 AD637 为基础的交流毫伏表设计 I 以 AD637 为基础的交流毫伏表设计 摘 要 在电量的测量中，电压，电流和频率是最基本的三个被测量。其中，电压量的测 量最为经常。而且随着电子技术的发展，更需要测量弱电的电压，所以毫伏电压表就 成为一种必不可少的测量仪器。另外，由于数字式仪器具有读数准确方便，精度高， 误差小，灵敏度和分辨率高，测量速度快等特点，而倍受用户青睐。 本系统以交流毫伏表为核心，以低功耗单片机 MCS-51 为主控制器，通过数据采 集系统采集数据，经设有运算放大电路和微型继电器的衰减模块输出，经衰减放大处 理的模拟信号，其中一路信号通过真有效值直流(RMS-DC)变换,经
2、 12 位快速逐次比 较式 A/D 转换器 AD574 芯片转换，实时把模拟量转化为数字量，经 CPU 进行计算、 处理后，由七段数码 LED 显示出来，最终实现对被测输入信号的电压值显示测量。 关键词 单片机 数字交流毫伏表 真有效值 II The AD637-based exchange mV table design Abstract In the measurement of electricity, voltage, current and frequency is the most basic measurement of the three. Among them, the vo
3、ltage measurement of the volume of the most often. In addition, with the development of electronic technology, but also the need for weak measurements of voltage, so mV voltage meter has become an indispensable instrument. In addition, as a result of digital equipment to facilitate accurate readings
4、 with high precision, small error, high sensitivity and resolution to measure the characteristics of speed, and greatly favored customers. MV of the system table to share as the core, low-power single-chip microcomputer-based MCS-51 controller, data acquisition system through data collection, the op
5、erator has a micro-amplifier and the attenuation of the relay output module, with attenuation enlarge analog signal processing, in which the signal all the way through the DC True RMS (RMS-DC) conversion, after 12 successive comparison fast A / D converter conversion AD574 chip, real-time analog to
6、digital conversion for, calculated by the CPU and processed, by the Seven-Segment LED digital display, the ultimate realization of the measured value of the input signal voltage and frequency measurement value display. Key words Single-chip microcomputer Digital AC Millivol 目 录 摘 要 . I Abstract .II 1 绪论 . 1 2 单片机. 2 2.1 单片机概述 . 2 2.2 单片机的内部结构 . 2 2.3 AT89C51 简介 3 2.4 单片机最小系统 9 3 单元电路设计 .10 3.1 衰减、放大倍数可调电路设计 .10 3.2 真有效值直流(RMS-DC)变换电路设计 .12 3.3 A/D 模数转换单元设计 15 3.3.1 A/D 转换器概述 .15 3.3.2 逐次逼近式 A
