high current output step dc-dc converter..need help

Discussion in 'The Projects Forum' started by ayane, Sep 25, 2009.

  1. ayane

    Thread Starter Active Member

    May 3, 2009
    39
    0
    Hi, i need to build a step-up converter which has an input range about 12v to 13.8v. The input needs to be step-up to 18.5/19v. The problem lies with the output current as it must be able to generate a max of 3.5A to the load.



    Any schematics or suggestions?..
     
  2. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    Why don't you try the National Semiconductor website:

    http://www.national.com/analog

    They have a Webench Designer, that comes up on the home page, that you input you parameters and they output a design using one of their parts. They provide a schematic, a detailed parts list to build the design, simulations of the design, and a lot of other details.

    It's a good place to start...
     
  3. ayane

    Thread Starter Active Member

    May 3, 2009
    39
    0
    thx very much...they did ask me to register by jotting down my personal details before i can use the software..

    Any reason or must i comply?
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Only if you want to use the software ;)

    They don't send out spam. Once in a while, they may send you a newsletter, but that's it.
     
  5. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    Just like SgtWookie said, I only receive a periodic email from them, and that may not be required. I read them because I find them useful, otherwise just mark them as spam and you will never see them again.

    It is very nice software for those designing power supplies, especially when you do not know where to start.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    No, don't mark them as spam; that may prevent other people using your ISP from receiving them.

    If you don't wish to receive the newsletters, use the instructions provided in the newsletter to unsubscribe from them.
     
  7. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    With efficincy losses, you will need to handle about 50W on the input side which (at 12V in) is an average current of over 4A. I'm not sure the simple switchers can do that, but you would need one rated for over 5A on the switch.
     
  8. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    This sounds like a laptop power supply to work in a car?

    They are standard item, I've had a couple off ebay. Unless building it is a specific project, it may well be cheaper to buy than make.

    Eg. (presently) ebay item 260472562852
    There are also companies like Lind which specialise in these units. The list prices are rather steep, but they also appear on ebay occasionally at a reasonable price.
     
  9. ayane

    Thread Starter Active Member

    May 3, 2009
    39
    0
    ya.i had been told to make one..but after designing my design throught the national semiconductor software.. I felt the price was quite high and the components will take quite sometime to arrive. In addition, the components were not easy to find.

    Hence, i was looking for a schematic with easily obtainable components.
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Old saying: "You can do it good, quick, or cheap...pick two." ;)

    Ken
     
  11. ayane

    Thread Starter Active Member

    May 3, 2009
    39
    0
    can this switcher do the job? LM2677..the input and output voltage suits and the output current but its a buck converter hence not very sure
     
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