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
    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
  2. RichardO

    Late Member

    May 4, 2013
    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. huang

    New Member

    Jan 8, 2014
    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.