want a solution for Variable O/P voltage SMPS

Discussion in 'General Electronics Chat' started by maheshjalgaonkar, Sep 14, 2012.

  1. maheshjalgaonkar

    Thread Starter New Member

    Sep 14, 2012
    I want to design a SMPS with variable O/P voltage eg. 4-30V with variable current eg. 0-3A.
    So sir I am confuse which topology is suitable for this application. please suggest me some solution. And if u have any reference then please forward me.
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Have a google for LM317 and LM338 circuits. :)
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    For SMPS you need to be using a pwm chip like the ones in an ATX psu,

    KA7500B http://ashleymckay.com/ashleymckay/cms/sites/default/files/KA7500B.pdf

    or TL494, http://www.datasheetcatalog.org/datasheet/motorola/TL494.pdf
    (note these are the same pinouts just different makers)

    for smaller currents up to 5a you can use the TL2844. these are found in a Laptop psu.


    here is a site with atx schematics http://danyk.wz.cz/s_atx_en.html

    I modified my atx psu to variable so you can save your self a bit of time and get an old psu and modify it for starters.
    It will give you an idea of how to design them.

    here are my videos, http://www.youtube.com/user/DodgyDavez?feature=CAQQwRs=
    Last edited: Sep 14, 2012
    absf likes this.
  4. Manish Anand

    New Member

    Jun 13, 2011
    See LM2576 datasheet.It's a 5 pin SMPS IC.There is a workable circuit available to suit your requirement
  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
    Do a standarad buck regulator using the simple switcher series like LM2576 or newer variants. The design software will pick all the components for you.