test gist

<SCRIPT LANGUAGE="JavaScript">

function calcBoost(form) {
vinmax=eval(form.vinmax.value);
vinmin=eval(form.vinmin.value);
voutmax=eval(form.voutmax.value);
voutmin=eval(form.voutmin.value);
freq=eval(form.freq.value);
iout=eval(form.iout.value);
vripple = eval(form.vripple.value);

// calculate duty cycle
minduty = 100*(1-vinmax / voutmin);
maxduty = 100*(1-vinmin / voutmax);
form.minduty.value = minduty;
form.maxduty.value = maxduty;

// calculate inductor values: D*Vin * (1-D) / (freq * 2 * Iout ) < L
// for vinmin and voutmin
D1 = (1-vinmin / voutmin);
L1 = D1 * vinmin * (1-D1) / (freq * 2 *iout);
// calculate for vinmin and voutmax
D2 = (1-vinmin / voutmax);
L2 = D2 * vinmin * (1-D2) / (freq * 2 *iout);
// calculate for vinmax and voutmin
D3 = (1.0-vinmax / voutmin);
L3 = D3 * vinmax * (1-D3) / (freq * 2 *iout);
// for vinmax and voutmax
D4 = (1.0-vinmax / voutmax);
L4 = D4 * vinmax * (1.0-D4) / (freq * 2.0 *iout);

L = Math.max(L1, L2, L3, L4);
form.minL.value = L * 1000000;

// Calculate peak current Ipk = (Vin * D)/(f * L)
// for vinmin and voutmin
Ipk1 = vinmin * D1 / (freq * L);
// for vinmin and voutmax
Ipk2 = vinmin * D2 / (freq * L);
// for vinmax and voutmin
Ipk3 = vinmax * D3 / (freq * L);
// for vinmax and coutmax
Ipk4 = vinmax * D4 / (freq * L);

Ipk = Math.max(Ipk1, Ipk2, Ipk3, Ipk4);
form.ipk.value = Ipk;

// Find the minimum capacitor Cap > Iout / (Vripple * freq)
cap = iout / (vripple * freq);
form.cap.value = cap * 1000000;

form.vdiode.value = voutmax;
form.idiode.value = Ipk;
}

</script>


  <div class="textblock"> <!-- InstanceBeginEditable name="text" -->
    <form>
<div align="center">
      <table width="75%" border=2  cellpadding=3>
        <tr>
          <td width="16%" align="center"><strong>Frequency</strong></td>
          <td width="18%"><div align="center">
              <input type="text" name="freq" value="31250" size=10> 
          Hz</div></td>
        <td width="66%">This is the boost converter frequency. For microcontrollers its often the CPU clock / 256        </tr>
        <tr>
          <td align="center"><strong>Min Vin</strong></td>
          <td><div align="center">
              <input type="text" name="vinmin" value="9" size=10>
            V</div></td>
          <td>The lowest expected input voltage                        </tr>
        <tr>
          <td align="center"><strong>Max Vin</strong></td>
          <td><div align="center">
              <input type="text" name="vinmax" value="12" size=10> 
            V </div></td>
        <td>The highest expected input voltage        </tr>
        <tr>
          <td align="center"><strong>Min Vout</strong></td>
          <td><div align="center">
              <input type="text" name="voutmin" value="30" size=10>
            V</div></td>
          <td>The  lowest desired output voltage        </tr>
        <tr>
          <td align="center"><strong>Max Vout</strong></td>
          <td><div align="center">
              <input type="text" name="voutmax" value="60" size=10>
            V</div></td>
        <td>The  highest desired output voltage        </tr>
        <tr>
          <td align="center"><strong>Iout</strong></td>
          <td><div align="center">
              <input type="text" name="iout" value="0.020" size=10> 
            Amps</div></td>
        <td>Output current draw        </tr>
        <tr>
          <td align="center"><strong>Vripple</strong></td>
          <td><div align="center">
            <input type="text" name="vripple" value="0.1" size=10>
            V
          </div></td>
        <td>Maximum allowable voltage ripple        </tr>
      </table>
      </div>
      <p align="center"><br>
        <input type=button value="Calculate!" onclick="calcBoost(this.form)">
      </p>
      
     <div align="center"> <table width="100%"  border="1" cellpadding="10">

        <tr>
          <th width="26%" scope="row">Min. Duty Cycle</th>
          <td width="56%"><strong>D</strong>min<strong> = 1 - (Vi</strong>max<strong>/Vo</strong>min<strong>)</strong></td>
          <td width="18%"><div align="center">
              <input name=minduty type=text value="" size="2" maxlength="2" > %
          </div></td>
        </tr>
        <tr>
          <th scope="row">Max. duty cycle</th>
          <td><strong>D</strong>max<strong> = 1 - (Vi</strong>min<strong>/Vo</strong>max<strong>)</strong></td>
          <td><div align="center">
              <input name=maxduty type=text value="" size="2" maxlength="2" > %
          </div></td>
        </tr>
        <tr>
          <th scope="row">Min. Inductor size</th>
          <td><strong> L &gt; D</strong><strong> * Vin * (1-D) / (freq * 2 * Iout ) </strong></td>
          <td><div align="center">
              <input name=minL type=text value="" size="5" maxlength="5" > uH
          </div></td>
        </tr>
        <tr>
          <th scope="row">Peak inductor current</th>
          <td><strong>Ipk = (Vin</strong>max<strong> * D)/(f * L)</strong></td>
          <td><div align="center">
              <input name=ipk type=text value="" size="5" maxlength="5" > A
          </div></td>
        </tr>
        <tr>
          <th scope="row">Minimum capacitor</th>
          <td><strong>Cap &gt; Iout / (Vripple * freq)</strong></td>
          <td><div align="center">
              <input name=cap type=text value="" size="5" maxlength="5" >
              uF
          </div></td>
        </tr>
        <tr>
          <td align="center"><strong>Minimum Schottky diode</strong></td>
          <td>Vbreakdown &gt;= Voutmax &amp; Idiode &gt;=Ipk</td>
          <td><div align="center">
            <input type="text" name="vdiode" value="" size=2>
            V
  <input type="text" name="idiode" value="" size=2>
            A </div>
        </tr>
      </table>
      </div>
    </form>
    <p>Don't forget that Duty cycle is the amount of time the switch is <strong>off</strong> / output is low. Be sure to measure the output voltages before connecting up anything important!    </p>
    <p>We like the J&amp;W Miller / Bourns RLB9012 inductors and other thru-hole from the same company</p>
    <p><a href="http://web.jfet.org/inGrid/">Thanks to Riad for some of the math!</a></p>
  <!-- InstanceEndEditable --> </div>
  <!-- InstanceEndRepeatEntry --><!-- InstanceEndRepeat --><div class="wikiinclude">
<!-- InstanceBeginEditable name="wikispace" --><!-- InstanceEndEditable -->
</div>