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<div class=WordSection1> <h1>Buck&#36716;&#25442;器的&#30005;流&#32441;波系&#25968;</h1> <p class=MsoNormal>Current Ripple Factor of a Buck Converter</p> <p class=MsoNormal><br> <br> </p> <h2 id="__Bookmark__0">摘要</h2> <p>&#30005;感和&#30005;容在 Buck &#36716;&#25442;器中构成低通&#28388;波器,此 LC &#28388;波器的&#36716;折&#39057;率&#24635;是&#35774;&#35745;得&#36739;低以便&#28388;除&#24320;&#20851;&#32441;波。常用的&#35774;&#35745;&#35268;&#21017;是,&#30005;感&#30005;流&#32441;波被&#35774;&#35745;成&#30005;感平均&#30005;流的 30% 左右。本文引入表&#36798;&#30005;感&#32441;波&#30005;流和其平均&#30005;流的比值的&#32441;波系&#25968;的概念并由它&#23548;出&#30005;感尺寸的表&#36798;式。通&#36807;利用面&#31215;&#31215;的概念和方法&#26469;&#35774;&#35745;&#30005;感,可以&#33719;得一&#20010;优化的&#32441;波系&#25968;范&#22260;,&#36825;&#23545;&#36827;行&#36716;&#25442;器&#35774;&#35745;&#26102;&#36873;&#25321;合适的&#30005;感具有很大的&#24110;助。</p> <p><br> <br> </p> <h2 id="__Bookmark__1">1. 介&#32461; </h2> <p>Buck &#36716;&#25442;器被&#24191;泛&#24212;用于大量的降&#21387;&#24212;用中,板上&#36127;&#36733;&#28857;&#36716;&#25442;器是&#36825;种&#24212;用的典型例子。&#20174;原理上看,它就是用一&#20010;功率&#24320;&#20851;和一&#20010;自&#21160;&#36816;行的&#32493;流二极管构成一&#20010;&#26025;波&#30005;路&#23558;&#36755;入&#30005;&#21387;&#21464;成一&#20010;矩形波,再通&#36807;一&#20010;低通 LC &#28388;波器&#28388;除高&#39057;&#24320;&#20851;&#32441;波和噪&#22768;以后生成一&#20010;基本上是&#32431;粹直流&#30005;&#21387;供&#32473;&#36127;&#36733;使用的&#30005;路。&#22270;1 &#26174;示了典型的Buck &#30005;路和他的&#24320;&#20851;波形。</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image001_zh-cn.jpg" ><img width=680 height=174 src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image001_zh-cn.jpg" alt="Technical Document Image Preview"></a><br> &#22270;1. (a) 典型的 Buck &#30005;路 (b) &#24320;&#20851;波形</p> <p>&#24403;功率&#24320;&#20851; Q1 &#23548;通&#26102;,&#32493;流二极管反向偏置,&#36755;入&#30005;流直接通&#36807; LC &#28388;波器流向&#36127;&#36733;;&#24403; Q1 &#20851;&#38381;&#26102;,&#30005;感&#30005;流 i<sub>L </sub>&#24378;制 D1 正向偏置&#23548;通。&#24320;&#20851;&#30005;&#21387;波形如&#22270;1所示&#20026;矩形&#33033;&#20914;。&#32463;&#36807; LC &#28388;波以后,假&#35774; LC &#28388;波器的&#36716;折&#39057;率&#36828;低于&#24320;&#20851;工作&#39057;率,&#36755;出&#30005;&#21387;基本上是&#32431;粹的直流&#29366;&#24577;。</p> <p>&#20174;&#28388;波器理&#35770;很容易理解到,增加&#30005;感、&#20943;小&#30005;容可以&#23548;致同&#26679;的&#36755;出&#32441;波效果,但是大&#30005;感&#20250;&#23548;致大体&#31215;和高成本的&#32467;果,反之,使用小&#30005;感&#21017;要求使用大&#30005;容,&#36825;并不是一&#20010;&#32431;粹的&#35774;&#35745;取舍&#38382;&#39064;。</p> <p>&#20026;了探&#35752;此&#38382;&#39064;,&#35753;我&#20204;&#20174;&#31283;&#24577;下的&#30005;感&#30005;流&#24320;始思考。</p> <p>&#24403;功率&#24320;&#20851;&#23548;通 (ON) &#26102;,加在&#30005;感上的&#30005;&#21387;是&#36755;入&#30005;&#21387;和&#36755;出&#30005;&#21387;之&#38388;的&#30005;&#21387;差:</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image002_zh-cn.jpg" ><img width=452 height=27 id="圖片 1" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image002_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#30005;感&#30005;流&#23558;&#20174; i<sub>L</sub>(0) &#24320;始&#32447;性增加:</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image003_zh-cn.jpg" ><img width=441 height=37 id="圖片 10" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image003_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#24403;功率&#24320;&#20851;截至 (OFF) &#26102;,加在&#30005;感上的&#30005;&#21387;与&#36755;出&#30005;&#21387;相同,但极性相反:</p> <p class=MsoNormal><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image004_zh-cn.jpg" ><img width=463 height=24 id="圖片 11" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image004_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>在此期&#38388;,&#30005;感&#30005;流&#23558;以斜率&#20174; i<sub>L</sub>(T<sub>on</sub>) &#24320;始&#32447;性&#20943;少:</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image005_zh-cn.jpg" ><img width=463 height=36 id="圖片 12" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image005_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>根据&#30005;感伏秒平衡的特性,很容易&#20174;式 (1) 和 (3) 得到&#30005;&#21387;&#20256;&#36755;比:</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image006_zh-cn.jpg" ><img width=463 height=37 id="圖片 13" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image006_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#36825;也就是占空比。与&#22270;1(b) &#36827;行比&#36739;,LC &#28388;波器工作起&#26469;就像一&#20010;平均函&#25968;,而占空比 D 就定&#20041;&#20026;&#24320;&#20851;管的&#23548;通&#26102;&#38388;和一&#20010;&#24320;&#20851;周期的比。</p> <p><br> <br> </p> <h2 id="__Bookmark__2">2. &#32441;波系&#25968; </h2> <p>&#22270;2 所示&#20026;&#30005;感&#30005;流波形。因&#20026;&#30005;感所受&#30005;&#21387;是矩形&#33033;&#20914;波,所以&#30005;感&#30005;流是包含一&#20010;支流分量的三角波。</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image007_zh-cn.jpg" ><img width=355 height=189 id="圖片 3" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image007_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#22270;2. &#30005;感&#30005;流波形&#30005;感&#32441;波&#30005;流值被定&#20041;&#20026;</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image008_zh-cn.jpg" ><img width=451 height=29 id="圖片 15" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image008_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>很明&#26174;,&#36127;&#36733;&#30005;流可表&#36798;&#20026;</p> <p class=MsoNormal><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image009_zh-cn.jpg" ><img width=448 height=38 id="圖片 16" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image009_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#32441;波系&#25968;可被定&#20041;&#20026;</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image010_zh-cn.jpg" ><img width=446 height=36 id="圖片 17" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image010_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#24403;&#32441;波系&#25968;小于2&#26102;,&#36716;&#25442;器工作在&#36830;&#32493;&#23548;通模式 (Continous Conduction Mode, CCM),否&#21017;就是非&#36830;&#32493;&#23548;通模式 (Discontinuous Conduction Mode, DCM)。由于&#36830;&#32493;&#23548;通模式下功率元件所受&#30005;流&#24212;力&#36739;低,工作在&#28385;&#36733;&#29366;&#24577;下的 Buck &#36716;&#25442;器一般都被&#35774;&#35745;成工作在&#36825;种模式下。因此,本文也只&#23545;&#36830;&#32493;&#23548;通模式&#36827;行&#35752;&#35770;。<br> <br> 等式(8)可以被表&#29616;&#20026;&#30005;&#21387;相&#20851;的形式:</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image011_zh-cn.jpg" ><img width=483 height=54 id="圖片 18" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image011_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#23545;于一&#20010;固定的&#30005;感量而言,&#36755;入&#30005;&#21387;越高,&#32441;波系&#25968;就越高。&#24403;&#36755;入&#30005;&#21387;固定&#26102;,&#30005;感量越小,&#32441;波系&#25968;就越高。&#32441;波系&#25968;越高,意味&#30528;流&#36807;&#30005;容的&#32441;波&#30005;流越大,&#23545;于相同的&#32441;波&#30005;&#21387;需求&#26469;&#35828;,就需要更大的&#30005;容量。</p> <p><br> <br> </p> <h2 id="__Bookmark__3">3. &#30005;感的面&#31215;&#31215; </h2> <p>&#20174;前面的描述中我&#20204;已&#32463;知道,&#24320;&#20851;&#23548;通期&#38388;&#30005;感&#20648;存能量,&#24320;&#20851;截至期&#38388;&#30005;感&#37322;放能量。&#20174;原理上&#35762;,&#36127;&#36733;&#30005;流&#20250;流&#36807;&#30005;感,所以足&#22815;的&#32447;圈空&#38388;是必&#39035;的。假如&#35774;&#35745;了&#36739;低的&#32441;波系&#25968;(或是&#36739;高的&#30005;感量),&#36739;多的&#32447;圈匝&#25968;就是必&#39035;的,&#36825;&#23558;&#23548;致更大的&#30005;感尺寸。我&#20204;要在&#36825;里引入一&#20010;面&#31215;&#31215; (Area Product, AP) 的概念&#26469;表征&#30005;感尺寸,它是磁芯的有效&#27178;截面&#31215;和&#32447;圈窗口面&#31215;的乘&#31215;,其&#21333;位是 m<sup>4</sup> 而不是表&#36798;体&#31215;的 m<sup>3</sup>,但面&#31215;&#31215;是和磁芯的体&#31215;成正比的。</p> <p>根据法拉第定律&#30005;感量 (L)、峰值&#30005;流 (i<sub>pk</sub>) &#20010;磁芯之&#38388;的&#20851;系可以表&#36798;&#20026;</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image012_zh-cn.jpg" ><img width=494 height=25 id="圖片 19" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image012_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>其中,i<sub>pk</sub> = i<sub>o</sub> + 1/2 Δi<sub>L</sub>,N 是&#32447;圈匝&#25968;,B<sub>m </sub>是磁芯的最大磁通密度,A<sub>C </sub>是磁芯的有效&#27178;截面&#31215;&#23545;于&#32447;圈,有下列等式成立</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image013_zh-cn.jpg" ><img width=497 height=36 id="圖片 20" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image013_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>其中,A<sub>WT </sub>&#32447;圈&#23548;体的&#27178;截面&#31215;,J &#23548;体中的&#30005;流密度,k<sub>W </sub>是磁芯的填充系&#25968;,W<sub>a </sub>是&#32447;圈窗口面&#31215;。&#32467;合 (10) 和 (11) 式,我&#20204;可以得到</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image014_zh-cn.jpg" ><img width=487 height=43 id="圖片 21" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image014_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#30005;感的&#30005;流有效值可用它的直流分量和交流分量&#26469;表&#36798;:</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image015_zh-cn.jpg" ><img width=495 height=47 id="圖片 22" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image015_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>等式 (12) 可被重&#20889;&#20026;</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image016_zh-cn.jpg" ><img width=492 height=82 id="圖片 23" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image016_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#22270;3 &#26174;示了磁芯在不同占空比下的&#24402;一化尺寸和&#32441;波系&#25968;之&#38388;的&#20851;系。</p> <p><a class="fancybox" href="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image017_zh-cn.jpg" ><img width=512 height=350 id="圖片 5" src="/content/dam/richtek-eds/resources/application-notes/an009/html-images-zh_cn/image017_zh-cn.jpg" alt="Technical Document Image Preview"></a></p> <p>&#22270;3. 不同占空比下&#32441;波系&#25968;和&#30005;感尺寸之&#38388;的&#20851;系</p> <p>&#24403;&#32441;波系&#25968;很低&#26102;,磁芯尺寸&#26174;著地增加;&#24403;&#32441;波系&#25968;&#36739;高&#26102;,磁芯尺寸几乎&#27809;有什么&#21464;化。&#36825;意味&#30528;在曲&#32447;拐&#24367;的&#21306;域存在一&#20010;最优化的地&#24102;。&#20174;原&#21017;上&#35762;,高&#32441;波系&#25968;意味&#30528;&#28388;波&#30005;容也要大,反之亦然。&#20030;例言之,&#24403;D= 0.3 &#26102;,&#32441;波系&#25968;可以&#35774;定在 0.2~0.4 之&#38388;,&#36825;&#26679;可以得到比&#36739;合适的磁芯尺寸和&#30005;容尺寸。</p> <p><br> <br> </p> <h2 id="__Bookmark__4">4. 一&#20010;&#35774;&#35745;示例 </h2> <p>一&#20010;&#24320;&#20851;工作&#39057;率&#20026; 300kHz 的 Buck &#36716;&#25442;器要在下列&#26465;件下工作:<br> Vin = 4 ~ 12V, Vout = 1.8V, Io = 6A, ΔVo = 10mV (&#36755;出&#30005;容上的&#32441;波&#30005;&#21387;)。&#35774;&#35745;中假&#35774;功率&#24320;&#20851;和&#32493;流二极管都是理想的,表1 &#26174;示了用&#20256;&#32479;方法按照 30% &#32441;波系&#25968;&#35745;算出的&#30005;感量,而按照本文提案的面&#31215;&#31215;方法得出的&#32463;&#36807;优化的&#35745;算&#32467;果在表2 中列出。</p> <p class=MsoNormal>表1. &#20256;&#32479;方法 30% &#32441;波系&#25968;&#35745;算&#32467;果</p> <div> <table class=MsoNormalTable border=1 cellspacing=0 cellpadding=0 width=550 style='width:412.5pt;border-collapse:collapse;border:none'> <tr> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;background:#009EB8; padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Input Voltage (V)</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Duty Cycle</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Ripple Factor</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Ripple Current (A)</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Ripple Current RMS (A)</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Inductance (μH)</p> </td> </tr> <tr> <td style='border:solid #009EB8 1.0pt;border-top:none;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>4</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.30</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.3</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.80</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.52</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.56</p> </td> </tr> <tr> <td style='border:solid #009EB8 1.0pt;border-top:none;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>8</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.15</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.3</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.80</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.52</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.89</p> </td> </tr> <tr> <td style='border:solid #009EB8 1.0pt;border-top:none;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>12</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.1</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.3</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.80</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.52</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>2.00</p> </td> </tr> </table> </div> <p class=MsoNormal>表2. 优化后方法&#35745;算&#32467;果</p> <div> <table class=MsoNormalTable border=1 cellspacing=0 cellpadding=0 width=550 style='width:412.5pt;border-collapse:collapse;border:none'> <tr> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;background:#009EB8; padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Input Voltage (V)</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Duty Cycle</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Optimal Ripple Factor</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Ripple Current (A)</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Ripple Current RMS (A)</p> </td> <td width=110 style='width:82.5pt;border:solid #009EB8 1.0pt;border-left: none;background:#009EB8;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>Inductance (μH)</p> </td> </tr> <tr> <td style='border:solid #009EB8 1.0pt;border-top:none;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>4</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.30</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.42</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>2.52</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.73</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.11</p> </td> </tr> <tr> <td style='border:solid #009EB8 1.0pt;border-top:none;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>8</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.15</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.45</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>2.7</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.78</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.26</p> </td> </tr> <tr> <td style='border:solid #009EB8 1.0pt;border-top:none;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>12</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.1</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.48</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>2.88</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>0.83</p> </td> <td style='border-top:none;border-left:none;border-bottom:solid #009EB8 1.0pt; border-right:solid #009EB8 1.0pt;padding:.75pt .75pt .75pt .75pt'> <p class=MsoNormal>1.25</p> </td> </tr> </table> </div> <p class=MsoNormal>在表1中,&#20256;&#32479;的&#35745;算方法&#35774;定了相同的&#32441;波&#30005;流值,因而&#36755;入&#30005;&#21387;&#36739;高&#26102;&#30005;感值就&#36739;大;而在表2中&#24212;用的是面&#31215;&#31215;的&#35745;算方法,不同&#36755;入&#30005;&#21387;下的&#30005;感量基本上是相同的,但&#36755;入&#30005;&#21387;&#36739;高&#26102;&#32441;波&#30005;流也&#36739;大。在&#23454;&#38469;的高&#39057;&#35774;&#35745;&#23454;&#36341;中,常常采用 POCAP 或 MLCC 作&#20026;&#36755;出&#30005;容,它&#20204;都具有极低的串&#32852;等效&#30005;阻,因此要得到&#32441;波&#30005;&#21387;指&#26631;是很容易的。</p> <p><br> <br> </p> <h2 id="__Bookmark__5">5. &#24635;&#32467; 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