【正文】 攀枝花學院本科畢業(yè)設計（論文） 基于單片機 數控式直流 恒流 源 設計 學生姓名： 學生學號： 202110501020 院（系 ）： 電 氣信 息 工程 學院 年級專業(yè)： 2021 級 電 子信息工程 指導教師： 劉衍平 (助教 /碩士 ) 二 〇一一年 六月 摘 要 I 摘 要 一般地，將輸出恒定的電流源稱為恒流源， “ 恒流源 ” 這個術語，原則上是指這樣一種穩(wěn)定電源：它輸出的電流與外部影響無關 即和負載改變大小無關 。實際上，大多數恒流源是用電子 電路實現的，而且僅當外部條件在一定的范圍內變化時才能保持輸出電流基本不變。 本系統(tǒng)以直流電流源為核心， AT89S52 單片機為主控制器，通過鍵盤來設置直流電源的輸出電流，設置步進等級可達 1mA，并可由 LCD1602 顯示 電流設定值和實際輸出電流值。本系統(tǒng)由單片機程控設定數字信號，經過 D/A 轉換器（ TLC5615）輸出模擬量，再經過運算放大器隔離放大，控制輸出功率管的基極， 隨著功率管基極電壓的變化而輸出不同的電流。單片機系統(tǒng)還兼顧對恒流源進行實時監(jiān)控，輸出電流經過電流 /電壓轉換后，通過 A/D 轉換芯片 (TLC2543)，實時把模擬量轉化為數據量，再經單片機分析處理，通過數字量形式的反饋環(huán)節(jié)，使電流更加穩(wěn)定，這樣構成穩(wěn)定的壓控電流源。實際測試結果表明，本系統(tǒng)能有效應用于需要高穩(wěn)定度的小功率恒流源的領域。 關鍵字 數控直流恒流源 ， 單片機 ， D/A 轉換器 ， A/D 轉換 ，電壓 /電流轉換器 攀枝花學院本科畢業(yè)設計 (論文 ) II ABSTRACT In this system the DC source is center and 89S52 version single chip microputer (SCM) is main controller, output current of DC power can be set by a keyboard which step level reaches 1mA, while the real output current and the set value can be displayed by LCD. In the system, the digitally programmable signal from SCM is converted to analog value by DAC (TLV5616), then the analog value which is isolated and amplified by operational amplifiers, is sent to the base electrode of power transistor, so an adjustable output current can be available with the base electrode voltage of power transistor. Using the keyboard to set the needed output current value, The SCM based on some specific algorithm to deal the certain settings for processing. Corresponding voltage output by the ADC output voltagecontrolled current source the other hand, The constant current source can be monitored by the SCM system realtimely, its work process is that output current is converted voltage, then its analog value is converted to digital value by ADC, finally the digital value as a feedback loop is processed by SCM so that output current is more stable, so a stable voltagecontrolled constant current power is designed. The test results have showed that this system, pared with the traditional regulated current source, has easy to operate and features high output current stability. Key words: Numerical control dc constantcurrent source， microcontroller， D/A converter， A/D conversion 目 錄 I 目 錄 摘 要 ........................................................................................................................................... I ABSTRACT ...................................................................................................................................... II 目 錄 ..............................................................................................................................................I 1 緒 論 ......................................................................................................................................... 1 2 數控直流恒流源系統(tǒng)描述 ....................................................................................................... 2 系統(tǒng)簡介 ................................................................................................................................. 2 系統(tǒng)總體設計 .......................................................................................................................... 3 方案論證 ................................................................................................................................. 3 主控器 ........................................................................................................................... 3 供電電源 ........................................................................................................................ 3 恒流源 ........................................................................................................................... 4 DAC和 ADC方案論證 ....................................................................................................... 5 鍵盤 ............................................................................................................................... 6 顯示 ............................................................................................................................... 6 3 系統(tǒng)硬件設計 ........................................................................................................................... 8 主控電路設計 .......................................................................................................................... 8 供電電源設計 ......................................................................................................................... 9 主電源 ........................................................................................................................... 9 單片機電源（第二級電源） .......................................................................................... 10 電源參數計算 [10] ........................................................................................................... 10 恒流源電路設計 ..................................................................................................................... 12 D/A 轉換電路設計 .................................................................................................................. 12 D/A和 A/D轉換器介紹 [12]............................................................................................. 12 理論分析與參數計算 [12] ................................................................................................. 16 測電路設計 ............................................................................................................................ 16 [2] .....................................................................................