DC/DC converter for supercapacitor

Discussion in 'The Projects Forum' started by rkrasowski, Jan 1, 2014.

  1. rkrasowski

    Thread Starter New Member

    Jul 10, 2012
    4
    0
    Happy New Year.
    The project that I am working required 5V for about 5 sec at max 400 mA (for BeagleBoneBlack to shot down nicely without corrupting micro SDcard in case of power failure). So I have 2 supercapacitors 10F 2.7V connected in series. What I need is a DC/DC converter to maintain output at 5V while input from capacitors is slowly going down to let's say 2.5V.
    I purchased NQR002AOX from Mauser.I connect as per example in data sheet, pin 5 to Rtrim, Pin2 Vin, Pin3 Gnd, Pin4 Vout(2.7 kΩ for Rtrim)
    but when I test the system it is not doing what I intended. My output almost exactly match input. So 5 V in - 5V out, 4V in, 4V out.

    Any idea which step-up converter would be useful for my application? What is wrong with NQR002AOX? Anybody did similar project??
    Thanks in advance
    Robert
     
  2. RichardO

    Well-Known Member

    May 4, 2013
    1,235
    384
    It is hard to tell from the data sheet but I think this may be a step down converter only.
     
  3. rkrasowski

    Thread Starter New Member

    Jul 10, 2012
    4
    0
  4. huang

    New Member

    Jan 8, 2014
    10
    0
    hi,we are dealing the DC DC converters,according to your cases,it's hard to work it matchly. we had the wide range input and the fixed output,the accuaracy of output can be 10%,look,you want the output work from 5V to 2.5V,this is out of the range.
     
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