Are there boost converters that can supply this much amperage?

[WAJIH]

Hey there. im also new to diy audio and to the while audio world.
Just a few question if anyone can help me.
say i want to build a boost converter for a 50 watt amp.
also say i am using a 4 ohm speaker for arguments sake.

that means:
p=v^2/R
v=sqrt(P*R)
= sqrt(50*4)
= 14v needed from boost converter

and that means

p=vi
i = p/v
= 50/14
=3.5amps needed from boost converter

the problem i need explaining is that boost converters can provide this 14v but not
3.5 amps. are there boost converters that can supply this much amperage?

i dont want to use dual unregulated power supply as transformers are way too expensive. and decided to go with boost converter as i can build a car amplifier from it.

please help me guys as i am still new to this stuff,

Much thanks,
Wajih

[gootee]

Sure!

Maybe you should go to national.com and use their on-line power supply designer. Or, go to linear.com and download their free SwitcherCADIII software (also known as LT-Spice). They also have wonderful Application Notes sections, with in-depth technical papers about switch-mode power supplies. And you can order free samples of the switcher chips that you will probably want to use.

In LT-Spice (free from linear.com), you can simply select "File" then "Switch Selector Guide" and input your specs, and it will design the power supply and simulate it for you, in seconds. Then you can change component values, for example, and simulate it again to see the effects. Using 12v as the input voltage and 14v out at 4 Amps, my 4-year-old version of the software shows at least six chips that Linear has (had), that would work, capable of producing from 7.0 Amps max to 17 Amps max, at 14v.

Later, you can go find out how to add an appropriate snubber, if needed, and maybe a better output filter and a post-regulator.

- Tom

[N-Channel]

Wajih,

This is not a problem. You can use a National SimpleSwitcher (say, LM2587) boost chip. It has a 5.0A current rating, and can stand off up to 65V. For 12.6V in, you will have no problem getting your required 3.53A out. Or, you can do a discrete regulator, using a UC3843 as the controller, and a N-Channel MOSFET as your switch. From there, follow classic boost regualtor design. Your power output levels are pretty much limited by the power dissipation capacity of the MOSFET, its V(dss), and Drain Current.

Hope this helps,

Steve

[WAJIH]

thanks guys for your help.

Yeah thanks guys for your reply. ive actually found quite a few good ics online but i have to purchase these online due to the fact that my local distributor doesnt sell these online.

HOwever i have found one ic that my local distributor sells and that is the "TL494 Pulsewidth Mod Cont CCT" this is apparantly by looking at datasheets a good ic to build a good DC Converter. its just i cant find any circuits online that use this chip for my requirement above.

if you can give me some ideas on how to use the datasheet for this ic to design my own circuit i would be thrilled. i find it quite hard to follow the datasheet for ics. any help would be great.

Kind Regards,
Wajih

[gootee]

Go to Google and in the search field enter:

TL494 boost schematic

But maybe you should consider using a different IC.