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<p>Maybe use an NPN emitter follower as a pass element instead of
the resistor. Doesn't load the converter, and you don't need heavy
duty zeners either. <br>
</p>
<p>I.e. Vout from the boost converter, via resistor 1k to the
transistor base, zener from base to gnd to delimit the voltage.</p>
<p><br>
</p>
<p>Best,</p>
<p> René<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">Am 16.02.2024 um 17:45 schrieb
Jean-Pierre Desrochers:<br>
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<p class="MsoPlainText">Hi all,<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">I’m using this type of stepup voltage
regulator to generate +15vdc and +30vdc<o:p></o:p></p>
<p class="MsoPlainText">From an incoming single +9vdc power
adapter.<o:p></o:p></p>
<p class="MsoPlainText">These BUCK’S converters generate very
good regulated voltage outputs but I noticed<o:p></o:p></p>
<p class="MsoPlainText">that on power up they ‘need’ to rise up
to around +48vdc<o:p></o:p></p>
<p class="MsoPlainText">Before settling down to their trimmed
voltages.<o:p></o:p></p>
<p class="MsoPlainText">Well these 2 voltages will supply a DSP
module @ +15vdc (not more !!!)<br>
and a dual opamp TL072 that has a maximum allowed supply
voltage of +/- 18vdc (36vdc overall).<o:p></o:p></p>
<p class="MsoPlainText">I tried putting a 16v zener diode in
parallel with the trimmed +15vdc<o:p></o:p></p>
<p class="MsoPlainText">But the BUCK goes wild (input current
rise up to around 2.5 amp and stays there !!)<o:p></o:p></p>
<p class="MsoPlainText">I also tried to put an RC circuit at the
input (33ohms + 100uf) of one of these BUCKs<o:p></o:p></p>
<p class="MsoPlainText">But again the modules rise its input
current to ‘try’ stabilize the regulation..<o:p></o:p></p>
<p class="MsoPlainText">Even with 100ohms resistors and 16v
zeners.. the BUCKs won’t start<br>
and finalise their outputs (inrush current installs).<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">So.. I’m stuck with this problem..<o:p></o:p></p>
<p class="MsoPlainText">Any possible solutions ???<o:p></o:p></p>
<p class="MsoPlainText"><span style="mso-ligatures:none"><img
style="width:13.5625in;height:13.3958in"
id="Image_x0020_5"
src="cid:part1.CAn0PQ0K.IWDSY02I@schmitzbits.de" class=""
width="1302" height="1286"></span><o:p></o:p></p>
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