need help with Step down voltage regulator

Discussion in 'The Projects Forum' started by sh@dowfax, Apr 29, 2009.

  1. sh@dowfax

    Thread Starter New Member

    Apr 29, 2009
    3
    0
    hi,
    I was asked to build a DC step down voltage regulator. The problem i am facin is that I have never done this sort of thing before and have absolutely no clue of how to do it. can any one please help. The requirements are

    input voltage - 18V
    Outuput voltage - 12V
    Output current - 2A
    Power rating - 24W
    He also wants mminimal amounts of ripple.
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Presumably "HE" is thinking of a switch-mode design since ripple was mentioned.

    Or is a linear regulator allowable?
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    2A at 6V drop, 12W. This is for analog. Switching is a lot more efficient, and cooler.
     
  4. sh@dowfax

    Thread Starter New Member

    Apr 29, 2009
    3
    0
    He is basically looking for a pulse width modulation through a timer triggered through a driver, which will give pulses into the circuit. I have attached a link of a picture which might give u some ideas

    http://ewb-uiuc.org/system/files/images/buck-converter.preview.png

    I am struggling to work out the values of the components.
    Thanks
     
  5. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    There is a nice Webench Power Designer tool at the National Semiconductor web site, www.national.com, that can be very useful at determining switching regulator devices as well as supporting components.
     
  6. sh@dowfax

    Thread Starter New Member

    Apr 29, 2009
    3
    0
    thanks for the info. it was good help.
    but I just realised that i didnt mention.
    I have access only to 555 timer.
    sorry for not being able to mention earlier
     
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