voltage regulator help - ot

[docwisdom]

Here is the full schematic, it includes the LED drivers instead of the mosfets.

[Acetronics2]

Hi, Doc


Looking back to your first post ... make me think using LM350 ( T or K ) or LM 338K's ( 5A )instead of the 317's would be a very good solution ... as it exists some insulating silicone pads ( or Mica sheets ...) and insulating spacers to avoid connecting reg.case to your aluminium casing !!!

The " best " solution surely is here !!!

See here i.e. : http://www.selectronic.fr/soussousfa...0&ssfam_ref=30

or here : http://www.selectronic.fr/soussousfa...0&ssfam_ref=20


Alain

[BigWumpus]

It's not easy for us to understand your problem.

You are mixing up linear regulators and switching regulators... we don't know what voltage and current you need...

I think you want to build a luminated heater. You want to burn away a lot of the electric power in your regulators in order to give a little piece of power to your LEDs.

Think about switching regulators !

[docwisdom]

The RGB led's need 4.5, 6.7, 7.6 volts respectivly and draw 350mA per color. for a total of 1.05 amps per LED unit.

I would like to run 7 or 8 of these in parallel, giving me the necessity for 8-9 amps of total current. So 3A per color.

so to break it down, I need [email protected], [email protected], and [email protected]. Each controlled via hpwm from the pic.


hope this clears it up

thanks
-brian

[NavMicroSystems]

...to break it down, I need [email protected], [email protected], and [email protected]. Each controlled via hpwm from the pic.

Brian,
Let's assume the average supply voltage is around 13V
that gives a total loss of about 60W!

Earlier you were talking about a "low power solution"

You should think about a different and more economical approach (switching rather than linear).

Don't focus on those expensive "fully integrated" switching regulators,
there are several "low cost" SMPS-controllers available that give good results and high efficiency if you use the right external components.
Take special care on the inductors, capacitors, mosfets and diodes
and last but not least the PCB layout.

With one of my current designs I get close to an efficiency of 90% at competitive costs.
(SEPIC Converter 120W - Input 8-18V Output 12V@10A)

[mister_e]

Welcome back Ralph! We miss you!

[docwisdom]

Ralph,
Thanks for the post.
I think you went over my head a little bit with SMPS and SEPIC. Could you throw out a couple specific examples for me, or a website reference?

thanks
-=brian