Capacitors for boost converter

Discussion in 'The Projects Forum' started by Andrew Mowry, Mar 30, 2015.

  1. Andrew Mowry

    Thread Starter New Member

    Mar 30, 2015
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    I'm designing a boost converter circuit using a Linear 1302-5, and it works well with aluminum electrolytics for the output capacitors, but I was hoping to clean up the output a bit by using os-con capacitors instead. I tried Panasonic os-con with the same capacitance/voltage rating as the electrolytics I'm currently using, but the converter doesn't work at all with them. Is there an obvious reason that I'm missing?? Linear recommends Sanyo os-cons, and I would have thought the Panasonics would be very similar.

    Thanks!
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
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    I can't think of any reason it shouldn't work.
     
  3. Andrew Mowry

    Thread Starter New Member

    Mar 30, 2015
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    It's odd, I've tried several electrolytics of different values and they all work, and several os-cons of different values, and none work at all.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    What does the converter do with the os-cons in place?
     
  5. Andrew Mowry

    Thread Starter New Member

    Mar 30, 2015
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    I haven't measured it, but it doesn't put out enough voltage/current to power the arduino I have it attached to.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    It could be that the low ESR of the os-con capacitors are causing instability in the converter control loop (sometimes the stability depends upon having a capacitor ESR value typical of electrolytics).
    You could add a small resistor (say 0.1 ohm) in series with the os-con capacitor to see if that helps, but that rather defeats your purpose of going to os-con capacitors to reduce ripple.

    What is a Linear 1302-5? I could not find any info on it.
     
  7. Andrew Mowry

    Thread Starter New Member

    Mar 30, 2015
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    Sorry, the correct part number is: LT1302CN8-5#PBF. Here's the link: http://www.linear.com/product/LT1302 Datasheet does specify low-ESR capacitors (SANYO os-cons), but I don't really know how much they would reduce noise (even if they did work ;)

    It's the converter that's used in the "MintyBoost" circuit, where they use electrolytics, but they're not concerned about noise. I'm trying to design an audio device and I get a little noise with the electrolytics, but it's not too bad if I use two output capacitors in parallel.
     
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