<p style="line-height:1.8;"><span style="font-size:14pt;">使用RA4L1-KB-V1.1和TPS5450做一个buck型的程控可调电源，使用LCD显示设置电压使用串口传输电压电流功率数据，按键调电压。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;"><img src="https://image.lceda.cn/oshwhub/pullImage/df099ad94c5e4ae68d7a6c7b855aaa62.jpg" width="861" height="646" alt="df099ad94c5e4ae68d7a6c7b855aaa62.jpg"></span></p> <p style="line-height:1.8;"><span style="font-size:14pt;"><img src="https://image.lceda.cn/oshwhub/pullImage/e5b9594c4c2f400e8621e9512cb6c804.jpg" width="858" height="643" alt="e5b9594c4c2f400e8621e9512cb6c804.jpg"></span></p> <p style="line-height:1.8;"><span style="font-size:14pt;"><img src="https://image.lceda.cn/oshwhub/pullImage/a6c1e786f7c64f9eb1461d4bc14c63d1.jpg" width="863" height="647" alt="a6c1e786f7c64f9eb1461d4bc14c63d1.jpg"></span></p> <h3 style="line-height:1.8;"><span style="font-size:14pt;">* 1、项目功能介绍</span></h3> <hr> <p style="line-height:1.8;"><span style="font-size:14pt;">主要是使用DAC电压结合KCL对TPS5450的FB反馈端电压调整，从而实现DAC调压功能。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">输入电压因为TPS54202HDDCR的限制不能大于28V。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">电压采集使用电阻分压。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">电流采集使用INA199A1DCKR高侧电流采集芯片。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">数据通过串口传给PC。</span></p> <h3 style="line-height:1.8;"><span style="font-size:14pt;">*2、项目属性</span></h3> <p>首次公开。</p> <p style="line-height:1.8;"> </p> <h3 style="line-height:1.8;"><span style="font-size:14pt;">* 3、开源协议</span></h3> <p style="line-height:1.8;">开源使用GPL3.0开源协议</p> <p style="line-height:1.8;"> </p> <h3 style="line-height:1.8;"><span style="font-size:14pt;">*4、硬件部分</span></h3> <hr> <p style="line-height:1.8;"><span style="font-size:18pt;">主要电路</span></p> <p style="line-height:1.8;"><img src="https://image.lceda.cn/oshwhub/pullImage/e2060fac4763446c81660de63e0b4ef1.png" alt="e2060fac4763446c81660de63e0b4ef1.png"></p> <p style="line-height:1.8;"><img src="https://image.lceda.cn/oshwhub/pullImage/9d61540200d8425c8abfdef0ea97c53d.png" alt="9d61540200d8425c8abfdef0ea97c53d.png"></p> <p style="line-height:1.8;"><img src="https://image.lceda.cn/oshwhub/pullImage/15656a0c861a4176a0add2f233356883.png" alt="15656a0c861a4176a0add2f233356883.png"></p> <p style="line-height:1.8;"><span style="font-size:14pt;">看TPS5450的数据手册知道 Vout=1.221+（R1/R2）*1.221；</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">TPS5450实现稳定降价压是看FB引脚电压。</span><br><span style="font-size:14pt;">VFB1.221时，输出电压下降。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">VFB=1.221时，输出电压下降。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">结合KCL来看我的输出电压公式：</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">（Vout-VFB）/R29+（VDAC-VD-VFB）/R33=VFB/R32</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">VFB=1.221V；</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">VD二极管压降，我使用的是SS14，实际测得是0.22V（有误差）</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">整理得出：</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">Vout=1.221+（R29/R32）*1.221 - (VDAC-0.22-1.221)*(R29/R33)</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">Vout=1.221+（16.923）*1.221 - (VDAC-1.441)*(14.666)</span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;">当VDAC1.441时,  Vour开始下降</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">由于RA4L1-KB-V1.1的DAC输出能力不足，再此电路中输出的最大电压为3.01V（有误差），但在此项目中在DAC电压到3V的范围是足够的。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">V=(VDAC-1.441)*(14.666)=(3-1.441)*(14.666)=22.864</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">要想DAC输出到3.3V可以加一个运放的电压跟随器，增强电流驱动能力。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">电阻分压电路</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;"><img src="https://image.lceda.cn/oshwhub/pullImage/9be21fe625cf43299f9da4eb0b0c6ade.png" alt="9be21fe625cf43299f9da4eb0b0c6ade.png"></span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">Vout=VADC*11；</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">电流采样电路</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;"><img src="https://image.lceda.cn/oshwhub/pullImage/d0ffd87a5c2f47bf9244cb4a08cf0c3f.png" alt="d0ffd87a5c2f47bf9244cb4a08cf0c3f.png"></span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">INA199A1DCKR自带50放大增益。</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">5V辅助电源</span></p> <p style="line-height:1.8;"><span style="font-size:14pt;"><img src="https://image.lceda.cn/oshwhub/pullImage/a422e86510294aa0891ee45ee3dae746.png" alt="a422e86510294aa0891ee45ee3dae746.png"></span></p> <p style="line-height:1.8;"> </p> <h3 style="line-height:1.8;"><span style="font-size:14pt;">*5、软件部分</span></h3> <hr> <p style="line-height:1.8;"><span style="color:#95a5a6;"><img src="https://image.lceda.cn/oshwhub/pullImage/5a5da9cabba34921aa21df14af61ede2.png" alt="5a5da9cabba34921aa21df14af61ede2.png"></span></p> <p style="line-height:1.8;"><span style="font-size:14pt;">代码部分没有什么高级的，就是普通的应用。</span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;">按键设置输出电压，开关输出。</span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;">串口打印数据。</span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;">因为DAC电压与输出电压不是线性的。</span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;">这是我记录部分数据：</span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;"><img src="https://image.lceda.cn/oshwhub/pullImage/1ddf526be11846d19e7f8cd045f90c43.jpg" width="821" height="999" alt="1ddf526be11846d19e7f8cd045f90c43.jpg"></span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;">我这里使用的是分段式函数</span></p> <p style="line-height:1.8;"><span style="font-size:18.6667px;"><img src="https://image.lceda.cn/oshwhub/pullImage/e85eda6be5984450b6b6b5d6aa9d3ac7.png" alt="e85eda6be5984450b6b6b5d6aa9d3ac7.png"></span></p> <h3 style="line-height:1.8;"><span style="font-size:18pt;">*电源纹波</span></h3> <table style="border-collapse:collapse;width:91.6206%;height:100.482px;"> <tr style="height:20.4297px;"> <td style="width:33.2938%;height:20.4297px;">Vout/V</td> <td style="width:33.2938%;height:20.4297px;">电流/A</td> <td style="width:33.2938%;height:20.4297px;">纹波/mv</td> </tr> <tr style="height:20.4297px;"> <td style="width:33.2938%;height:20.4297px;">5</td> <td style="width:33.2938%;height:20.4297px;">1</td> <td style="width:33.2938%;height:20.4297px;">117</td> </tr> <tr style="height:20.4297px;"> <td style="width:33.2938%;height:20.4297px;">5</td> <td style="width:33.2938%;height:20.4297px;">5</td> <td style="width:33.2938%;height:20.4297px;">150</td> </tr> <tr style="height:19.5964px;"> <td style="width:33.2938%;height:19.5964px;">12</td> <td style="width:33.2938%;height:19.5964px;">1</td> <td style="width:33.2938%;height:19.5964px;">167</td> </tr> <tr style="height:19.5964px;"> <td style="width:33.2938%;height:19.5964px;">20</td> <td style="width:33.2938%;height:19.5964px;">1</td> <td style="width:33.2938%;height:19.5964px;">100</td> </tr> </table> <p> </p> <p><span style="font-size:14pt;">电源纹波有点大。</span></p> <p><span style="font-size:14pt;">有可能是我测量问题，也有可能PCB问题，输出电容问题。后两者的可能性很高，我是用TPS5450画过一个电源模块，5V1A时纹波才50~60mV真的很低。</span></p> <h3 style="line-height:1.8;"><span style="font-size:14pt;">*6、BOM清单</span></h3> <hr> <p style="line-height:1.8;"><img src="https://image.lceda.cn/oshwhub/pullImage/39d2ade07f0b4161bb4d98794388005d.png" alt="39d2ade07f0b4161bb4d98794388005d.png"></p> <p style="line-height:1.8;"> </p> <h3 style="line-height:1.8;"><span style="font-size:14pt;">*7、大赛LOGO验证</span></h3> <hr> <p style="line-height:1.8;"><img src="https://image.lceda.cn/oshwhub/pullImage/d75ed872a1f7423abfee8b125c7da673.jpg" width="706" height="941" alt="d75ed872a1f7423abfee8b125c7da673.jpg"></p> <p style="line-height:1.8;"><img src="https://image.lceda.cn/oshwhub/pullImage/665bbb889e7d42e9a9c05d701f63cee4.jpg" width="688" height="917" alt="665bbb889e7d42e9a9c05d701f63cee4.jpg"></p> <p style="line-height:1.8;"> </p> <p style="line-height:1.8;"> </p> <h3 style="line-height:1.8;">* 8、演示您的项目并录制成视频上传</h3> <hr> <p style="line-height:1.8;"> </p> <p style="line-height:1.8;"><span style="font-size:14px;"><a href="/posts/42551e8f2f2548cabc1c36626a42da94" target="_blank">前往查看更多详情 ＞</a></span></p> <p style="line-height:1.8;"> </p>