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Author I Need buck-boost 18volts@12 amp Converter
zz

2007-03-20, 9:25 am

Hi Guys, I need to boost and regulate a cars power system from 11.5 v
(drained batt) to 15 volts input (max alt. charging), to a regulated 14~18
volts @ 10~12 amps, about 140~200 watts.
I cant find a schematic or design for more than 5 watts. The closest thing
I can think of would be a 100 watt Computer Laptop mobile power supply that
plugs into the cigeratte lighter.
I dont need tight regulation, 0.25 volt ripple is OK.
I'm hoping to build something for less than $15.
Any ideas? Thanks......


Palindrome

2007-03-20, 9:25 am

zz wrote:
> Hi Guys, I need to boost and regulate a cars power system from 11.5 v
> (drained batt) to 15 volts input (max alt. charging), to a regulated 14~18
> volts @ 10~12 amps, about 140~200 watts.
> I cant find a schematic or design for more than 5 watts. The closest thing
> I can think of would be a 100 watt Computer Laptop mobile power supply that
> plugs into the cigeratte lighter.
> I dont need tight regulation, 0.25 volt ripple is OK.
> I'm hoping to build something for less than $15.
> Any ideas? Thanks......
>
>


Can the output be floating, or does it need a common ground with the supply?

If floating:

Start with the circuit for a 12v 250W rms bridge audio/servo amplifier
and then drive it with a frequency of your choice. Take the output, full
wave rectify and smooth it and sample it to give a voltage to control
the frequency generator output amplitude.

If common ground:

Stick a 1:1 transformer with appropriate ratings between output and
rectifier.


--
Sue






zz

2007-03-21, 3:25 am

Hi Sue, it's commom ground, thanks for the input. I dont think I can meet
my target price.

"Palindrome" <me9@privacy.net> wrote in message
news:qJOLh.59890$aL1.25960@fe12.news.easynews.com...
> zz wrote:
>
> Can the output be floating, or does it need a common ground with the
> supply?
>
> If floating:
>
> Start with the circuit for a 12v 250W rms bridge audio/servo amplifier and
> then drive it with a frequency of your choice. Take the output, full wave
> rectify and smooth it and sample it to give a voltage to control the
> frequency generator output amplitude.
>
> If common ground:
>
> Stick a 1:1 transformer with appropriate ratings between output and
> rectifier.
>
>
> --
> Sue
>
>
>
>
>
>



TimPerry

2007-03-21, 3:25 am

zz wrote:[color=darkred]
> Hi Sue, it's commom ground, thanks for the input. I dont think I can
> meet my target price.
>
> "Palindrome" <me9@privacy.net> wrote in message
> news:qJOLh.59890$aL1.25960@fe12.news.easynews.com...

how about a 6 volt golf cart battery with the negative going to the cars
+13.8? a stack of 10A or so diodes would drop the voltage down to desired
level


Palindrome

2007-03-21, 3:25 am

zz wrote:

>
> "Palindrome" <me9@privacy.net> wrote in message
> news:qJOLh.59890$aL1.25960@fe12.news.easynews.com...
>
> Hi Sue, it's commom ground, thanks for the input. I dont think I can

meet
> my target price.



Here follows a link to a design for a +11V to 14.3V Input to 16V at 70
Watts (4.4A):

http://www.maxim-ic.com/cookbook/po.../pdfs/CB115.pdf

Maxim provide a wide range of completed design exercises ("cookbook"):

http://www.maxim-ic.com/cookbook/po...der=en_topology

Plus application notes:

http://www.maxim-ic.com/appnotes10....k/20/asc_pk/126

Feeding the Max668 partnumber in will give you all the information you
need to modify the circuit for 200W output and design a unit:

http://www.maxim-ic.com/appnotes10....lter/partnumber


However, it can be done by paralleling up the inductor, switch and
rectifier components and increasing the capacitor bank. This will
probably be a lot cheaper than sourcing the inductor needed for 200W in
one go.

--
Sue
LinkBot





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