基于单片机简易数控直流电压源的设计

基于单片机简易数控直流电压源的设计

摘 要

本设计以AT89S52单片机为核心控制芯片，实现数控直流电源功能的方案。设计采用8位精度的DA转换器DAC0832、三端可调稳压器LM350和一个UA741运算放大器构成稳压源，实现了输出电压范围为＋1.4V～+9.9V，电压步进0.1V的数控稳压电源，最大纹波只有10mV，具有较高的精度与稳定性。另外该方案只采用了5个按键实现输出电压的方便设定，具有设定值调整，微调（步进量0.1），粗调（步进量1）三种调整功能，显示部分我们采用了三位一体的数码管来显示输出电压值。我们自行设计了

?12V和5V电源为系统供电。该电路的原理是通过MCU控制DA的输出电压大小，通过放大器放大，放大后的电压作为LM350的参考电压，真正的电压还是由电压模块LM350输出。利用5个按钮调整电压、并且通过共阴极三位一体LED显示输出的电压值。设计使用3三位一体数码管，可以显示三位数，一个小数位，比如可以显示5.90V，采用动态扫描驱动方式。与传统的稳压电源相比具有操作方便，电源稳定性高以及其输出电压大小采用数码显示的特点。

关键词：数控，步进，三端可调稳压器

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基于单片机简易数控直流电压源的设计

ABSTRACT

The design is with the MCUAT89S52 for the core control chip,which carry out the project that the function of the number controls the direct current power supply.Designed with the precision of eight DA converter DAC0832, three-adjustable regulators LM350 and a UA741 Operational Amplifiers constitute Regulators source, the output voltage range of +1.4 V ~ +9.9 V, 0.1V voltage step NC Regulators Power, it has with high precision and stability and only have the biggest ripple of 10 mV. Meanwhile, the program used only five keys to achieve the convenience of the output voltage setting ,with setting value adjustments. It has three kinds of adjust function,which can carry out micro-adjustment (Stepping volume 0.1)and the coarse adjustment (Stepping volume 1). The show part we have adopted a three-dimensional digital pipe to show the output voltage value. And we designed the

?12V and 5V power supply system for electricity. The principle of that electric circuit was that the output voltage size which passes the MCU to control DA, passing the amplifier amplification, and the voltage is the reference voltage of the LM350. And the real voltage is still the LM350 outputs are from the voltage mold piece. Making use of five buttons to adjustment voltages, and pass the total cathode Christian Trinity LED to display the output's voltage .In this design I used 3 piece code tubes, which can show three position numbers, one of them is a fraction position. for example ,it can show a 5.90 Vs. In this design I adopt the scan to drive way is dynamic state sweep. With traditional steady press power supply to compare to have an operation convenience, the power supply stability high characteristics, its exportation electric voltage size adoption figures show.

Keywords: Numerical Control, Stepping,Three-adjustable regulators

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基于单片机简易数控直流电压源的设计

目 录

第1章 绪论 ············································································ 1

1.1 研究背景及意义 ·············································································· 1 1.2 国内外研究状况 ·············································································· 1 1.3 课题研究方法 ················································································· 2

第2章 数控电压源的总体方案介绍··············································· 3

2.1 数控电压源的方案论证 ····································································· 3 2.1.1 方案一：采用单片机的数控电压源的设计 ······································· 3 2.1.2 方案二：采用调整管的双计数器的数控电压源的设计 ························ 3 2.1.3 方案三：采用调整管的十进制计数器的数控电压源的设计 ·················· 4 2.2 数控电压源的方案比较 ······································································· 5 2.2.1 数控部分的比较 ········································································ 5 2.2.2 输出部分的比较 ········································································ 5 2.2.3 显示部分的比较 ········································································ 5

第3章 数控电压源的工作原理 ···················································· 6

3.1 整机电路框图 ··························································································· 6 3.2 工作原理 ······················································································· 6 3.2.1 DA转换电路工作原理 ································································· 6 3.2.2 电压调整电路工作原理 ······························································· 7 3.2.3 数值计算 ················································································· 8

第4章 单元电路工作原理 ·························································· 9

4.1 时钟电路 ······················································································· 9 4.1.1 时钟振荡电路图 ········································································ 9 4.1.2 时钟信号的产生 ········································································ 9 4.2 复位电路 ······················································································· 9 4.3 键盘接口电路 ··············································································· 10 4.3.1 键盘电路 ··············································································· 10 4.3.2 键盘电路工作原理 ··································································· 10 4.4 显示接口电路 ················································································ 11

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