编号
毕业设计(论文)
基于单片机的程控D类音频功率放大器
Programmable Class-D Audio Power Amplifier Based on MCU
学院名称 专业名称 学生姓名 学
号
指导教师
2015年6月28日
本科生毕业设计（论文）
摘 要
基于单片机的程控D类音频功率放大器主要运用基本电子技术基础、单片机控制技术、D 类音频功率放大技术、功率变换技术等专业知识，设计由通用型单片机控制实现的程控 D 类音频功率放大器，具有基本的双路音频功率放大功能、单片机程控音频回啸检测抑制等功能。
本设计是基于MSP430单片机及其外围的控制电路来实现的。主要由七大部分组成：拾音电路、程控电路、D类音频功率放大器、主控单元，啸叫检测，回啸抑制以及开关稳压电源电路。由单片机程控音频功率放大器、检测并抑制啸叫。D类音频功率放大器采用D类音频功率放大器专用芯片，由H 桥作为功率输出级，使得其输出没有传统的 LC 滤波器的情况下可直接驱动感性负载，它的输出功率较大，失真小，且具有过载保护功能。开关稳压电源提供12V直流电源为D类音频功率放大器供电，再经降压为单片机提供3.3V的直流电。拾音电路通过单片机控制检测回啸并用带阻滤波器程控抑制回啸，将音频输入程控D类音频功率放大器。
该系统具有效率高、功耗低、体积小，专业性强等显著优点，可以满足各类用户的音频功放和高保真的要求，主要在汽车音响、教育教学、便携式音响系统和大功率音频视频等领域有广泛的应用。
关键词： D类功率放大器；功率放大器; 啸叫检测；回啸抑制
I
本科生毕业设计（论文）
Abstract
Programmable Class-D audio power amplifier based on MCU mainly uses professional knowledge like basic electronic technology, MCU control technology, Class-D audio power amplifier technology and power conversion technology This graduation project mainly designs programmable Class-D audio power amplifier based on MUC, it is a programmable Class-D audio power amplifier of real-time detecting and suppressing the howling by MUC, with a basic two-way audio power amplification function and howling suppression function.
The programmable class-D audio power amplifier design is achieved on the basis of MSP430 MCU and peripheral control circuits. It is mainly divided into seven parts: pickup circuit, programmable circuit, and Class-D audio amplifier, the main control unit, howling detection, howling suppression and switching mode power supply. The system adopts MCU to control Class-D audio power amplifier, and to detect and suppress the howling. Class-D audio power amplifier adopts Class-D audio power amplifier ASIC, which uses H-bridge as a power output stage so that it can directly drive inductive load，its output power is larger, distortion is low. The system adopts switching power supply to provide a 12V DC power to, Class-D audio power amplifier and then reduce pressure to provide 3.3V DC power to MCU. Pickup circuit, detect the howling by MCU and suppress the howling by band-stop filter, finally input the audio to the programmable class-D audio power amplifier.
This system has high efficiency, low power consumption, small size and other significant advantages. It meets users’ requirements of audio power amplifying and high definition, and it is mainly used in the field of car audio, education, portable sound system and power audio video.
Key words: Class-D power amplifier; power amplifier; howling detection; howling suppression
II
本科生毕业设计（论文）
目 录
摘 要 .............................................................................................................................................................. I Abstract ......................................................................................................................................................... II 第1章 绪论 ................................................................................................................................................... 1
1.1音频功率放大器的设计背景 ........................................................................................................... 1 1.2 D类音频功率放大器国内外发展现状 ........................................................................................... 2 1.3主要技术指标 ................................................................................................................................... 2 1.4本章小结 ........................................................................................................................................... 3 第2章 系统整体设计及各单元方案论证 ................................................................................................... 4
2.1系统整体设计框图 ........................................................................................................................... 4 2.2系统总体方案分析 ........................................................................................................................... 4 2.3各部分单元方案论证 ....................................................................................................................... 5
2.3.1主控单元电路设计 ................................................................................................................ 5 2.3.2 D类音频功率放大器电路 .................................................................................................... 6 2.3.3拾音电路 ................................................................................................................................ 7 2.3.4带阻滤波电路 ........................................................................................................................ 8 2.3.5开关稳压电源电路 ................................................................................................................ 8 2.4本章小结 ........................................................................................................................................... 9 第3章 各单元硬件电路设计 ..................................................................................................................... 10
3.1主控单元电路设计 ......................................................................................................................... 10
3.1.1芯片介绍 .............................................................................................................................. 10 3.1.2工作原理 .............................................................................................................................. 12 3.1.3主控单元最小系统 .............................................................................................................. 12 3.2 D类音频功率放大器电路设计 ..................................................................................................... 13
3.2.1芯片介绍 .............................................................................................................................. 13 3.2.2工作原理 .............................................................................................................................. 14 3.2.3硬件电路图 .......................................................................................................................... 16 3.3拾音电路及带阻滤波器电路设计 ................................................................................................. 16
3.3.1芯片介绍 .............................................................................................................................. 16 3.3.2工作原理 .............................................................................................................................. 17 3.3.3硬件电路图 .......................................................................................................................... 18 3.4程控电路设计 ................................................................................................................................. 19
3.4.1芯片介绍 .............................................................................................................................. 19 3.4.2工作原理 .............................................................................................................................. 20 3.4.3硬件电路图 .......................................................................................................................... 21 3.5开关电源稳压电路设计 ................................................................................................................. 21
III
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