<p class="MsoNormal" style="margin:0cm 0cm 0pt"><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">运算放大器是采用双运算,</span><span lang="EN-US"><font face="Times New Roman">U1A</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">一个作为跟随器,另外</span><span lang="EN-US"><font face="Times New Roman">U1B</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">是作为比较器,</span><span lang="EN-US"><font face="Times New Roman">R5</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">,</span><span lang="EN-US"><font face="Times New Roman">R7</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">,</span><span lang="EN-US"><font face="Times New Roman">R6</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">,和</span><span lang="EN-US"><font face="Times New Roman">D1</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">是形成一个电压基准的,与</span><span lang="EN-US"><font face="Times New Roman">U1B</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">过来的电压进行比较,去控制</span><span lang="EN-US"><font face="Times New Roman">Q1</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">的导通程度。</span><span lang="EN-US"><font face="Times New Roman">R9</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">,</span><span lang="EN-US"><font face="Times New Roman">R10</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">是电压取样电阻,</span><span lang="EN-US"><font face="Times New Roman">R3</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">是保护电阻。通过电流的大小,就改变了</span><span lang="EN-US"><font face="Times New Roman">U1B5</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">脚的电压大小。</span></p><p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US"><font face="Times New Roman"><span style="mso-spacerun:yes"></span></font></span></p><p class="MsoNormal" style="margin:0cm 0cm 0pt"><span lang="EN-US"><font face="Times New Roman"><span style="mso-spacerun:yes"></span>R6</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">是调整</span><span lang="EN-US"><font face="Times New Roman">U1A3</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">脚的基准电压大小,是控制恒流电流值的调整点。</span><span lang="EN-US"><font face="Times New Roman">C1</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">,</span><span lang="EN-US"><font face="Times New Roman">C2</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">,</span><span lang="EN-US"><font face="Times New Roman">C3</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">是消除寄生震荡的电容。</span><span lang="EN-US"><font face="Times New Roman">C4</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">是用来吸收尖峰浪涌电流的,用来保护</span><span lang="EN-US"><font face="Times New Roman">LD1</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">的。</span></p><p class="MsoNormal" style="margin:0cm 0cm 0pt"><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">其他就是按钮,电池了。另外</span><span lang="EN-US"><font face="Times New Roman">LM358</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">最小工作电压,根据生产厂家的不同,最低工作电压也不相同,如国家半导体的,就可以工作在</span><span lang="EN-US"><font face="Times New Roman">2</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">。</span><span lang="EN-US"><font face="Times New Roman">4V</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">!其他厂家的一般在</span><span lang="EN-US"><font face="Times New Roman">3V</font></span><span style="font-family:宋体;mso-ascii-font-family:'times new roman';mso-hansi-font-family:'times new roman'">左右。</span></p><p>[em01]</p><p>实际上电路还可以进一步简化:</p>
<br />这样运算放大器可以使用LMV321单运算放大器了,LMV321的最低工作电压为1.8V!完全可以适用于3V的电路中了。电压基准使用美信公司的1.2V电压基准:MAX6001EUR,只要电源电压高于基准电压的0.5V就可以很好的工作。你查查相关器件资料就可以做PCB了。剩下的我就不多说了。 [此帖子已经被作者于[lastedittime]1180918898[/lastedittime]编辑过] |