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

Thread Starter

ayane

Joined May 3, 2009
39
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?..
 
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...
 

Thread Starter

ayane

Joined May 3, 2009
39
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?
 

SgtWookie

Joined Jul 17, 2007
22,220
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.
 
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.
 

SgtWookie

Joined Jul 17, 2007
22,220
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.
 

bountyhunter

Joined Sep 7, 2009
2,512
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?..
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.
 

rjenkins

Joined Nov 6, 2005
1,013
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.
 

Thread Starter

ayane

Joined May 3, 2009
39
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.
 

Thread Starter

ayane

Joined May 3, 2009
39
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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