电气自动化专业毕业论文---LED照明恒流驱动电源的设计.docVIP

摘 要 本次设计为LED的照明恒流驱动电源，系统大致分为五个模块：单片机控制模块、数模（D/A）转换模块、恒流源模块、模数（A/D）转换模块、显示模块。单片机控制模块以单片机AT89S52为核心，通过键盘预置电流值，单片机输出相应的数字信号给D/A转换器，D/A转换器输出的模拟信号送到运算放大器，通过恒流源控制主电路电流大小。实际输出的电流再通过采样电阻采样变成电压信号，经A/D转换后将信号反馈到单片机中。单片机将反馈信号与预置值比较，根据两者间的差值调整输出信号大小。显示模块采用LED显示屏与8255连接设计成10进制8位数码动态显示电路。键盘模块采用常见4×4矩阵键盘，用动态扫描方式读取外部按键动作，这样设计可靠，配合AT89S52单片机可以很轻松的实现按键输入 。此外，本设计可实现输出电流100～1000mA且有步进调整功能。 关键词 ： 单片机； 键盘控制； D/A转换； 恒流源 ； A/D转换； 译码显示 ABSTRACT The design for the LED lighting constant current driver, the system can be divided into five modules: a single-chip control module, D / A( D / A ) conversion module, a constant current source module, module ( A / D ) conversion module, display module. Single chip control module on AT89S52 single-chip microcomputer as the core, through the keyboard to preset current value, the output of the single chip digital signal corresponding to the D / A converter, D / A converter output analog signal to the operational amplifier, through a constant-current source control main circuit current size. The actual output current through the sampling resistor sampling is changed into voltage signal, the A / D conversion signal feedback to the mcu. MCU feedback signal and the preset value will be compared, according to the difference between the two output signal for adjusting the size of. Display module using LED display screen and the 8255 connection is designed into 10 binary 8 bit digital dynamic display circuit. Keyboard module uses a common 4 x 4 matrix keyboard, using dynamic scanning mode to read the external button action, so the design of reliable, with AT89S52 MCU can easily achieve the key input. In addition, the design can realize the output current of 100 ~ 1000mA and step adjustment function. Key words: single chip microcomputer; keyboard control; D / A conversion; constant 目 录 1 绪论 1 1．1 引言 1 1．2 LED发展现状及应用意义和前景 1 1．2．1国内外应用及发展现状 1 1．2．2 课题研究意义 2 2 总体结构设计与论证 4 3 硬件电路设计 7 3．1 单片机模块的设计 7 3．1．1 单片机的选择 7 3．1．2 AT89S52单片机功能特性描述 7 3．1．3 AT89S52引脚功能描述