Which topology for isolated AC/DC @ 120W ?

[R Jones]

Hi.

I am looking to build an isolated SMPS that takes 120/240 AC and provides
DC, 0 - 12 V output, loads 0 to 10 A. I am looking for suggestions on
topology and magnetic / switch selections.

The PS will drive high-power/high-output LEDs, so I will need to run it in
constant-current mode. I'm hoping to be able to use it in CV mode as a
bench-type PS at some point too.

Can this be built with off-the-shelf magnetics or do I need to roll my own
transformers/cores?

I've heard the flyback's useful range is about ~100W, but will require
custom magnetics.

I've built DC-DCs before, boost & buck, no AC/DC.

Thank you.
Richard.

 

[Pooh Bear]

Hi.

I am looking to build an isolated SMPS that takes 120/240 AC and provides
DC, 0 - 12 V output, loads 0 to 10 A. I am looking for suggestions on
topology and magnetic / switch selections.

The PS will drive high-power/high-output LEDs, so I will need to run it in
constant-current mode. I'm hoping to be able to use it in CV mode as a
bench-type PS at some point too.

Can this be built with off-the-shelf magnetics or do I need to roll my own
transformers/cores?

I've heard the flyback's useful range is about ~100W, but will require
custom magnetics.

I've built DC-DCs before, boost & buck, no AC/DC.

Flyback is fine at that power.

Go to www.powerint.com and download as many of their fabulous app notes as you
care to read. They cover just about every imaginable aspect of flyback
designs. They also have a simple CAD program that will calculate all the
magnetics info you need and it's tweakable too !

Be aware of safety regs implications with AC-DC converters. I like to use
triple insulated wire to get the necessary isolation and I recommend it. Makes
for more efficient use of the winding area too.

Graham

 

[Genome]

Hi.

I am looking to build an isolated SMPS that takes 120/240 AC and provides
DC, 0 - 12 V output, loads 0 to 10 A. I am looking for suggestions on
topology and magnetic / switch selections.

The PS will drive high-power/high-output LEDs, so I will need to run it in
constant-current mode. I'm hoping to be able to use it in CV mode as a
bench-type PS at some point too.

Can this be built with off-the-shelf magnetics or do I need to roll my own
transformers/cores?

I've heard the flyback's useful range is about ~100W, but will require
custom magnetics.

I've built DC-DCs before, boost & buck, no AC/DC.

Thank you.
Richard.

Don't ponce about. Use a forward converter.

Flyback converters are heathen bits of shit dirt.

You want low noise? You want decent transient performance? You want wide
range output setting? You DO NOT want a fucking flyback converter. People
who do that sort of shit play dungeons and dragons and have permanent
vacuous grins on their faces. They do it, then **** off and leave someone
else to sort the shit out.

Guy Macon would insist that you use a flyback converter.

DO YOU FUCKING UNDERSTAND WHAT I AM TRYING TO SAY HERE!!!!??????

DNA

 

[Paul Mathews]

If you're really keen on doing your own, there is much to learn. Don't
try anything more exotic than a 2-switch forward converter. There are
lots of design resources at the TI, On Semi, Fairchild, ST, and Power
Integrations websites. However, if you just need to get the job done
and realize that life is short, look for a nice Xantrex bench supply in
the used market.
Paul Mathews