Read carefully. It seems I have always underestimated the technological progress... :-)
Best regards, Piotr
Read carefully. It seems I have always underestimated the technological progress... :-)
Best regards, Piotr
I think they forgot the "m". 350mW?
A common shorthand, what they mean is for a typical (probably [active clamp] flyback or the like) topology with that as the DC supply.
Digi-Key's catalog shows a similar shorthand on hundreds of parts.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design
And a generous interpretation indeed of "planar" IMHO.
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No. These planar transformers are impressive.
Coilcraft has planars up to 800 watts.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Probably forward converter, which doesn't have to store energy so allows a small core.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The windings are planar, namely PC boards,
One can build transformers like this with the windings part of the main power supply PCB.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
snipped-for-privacy@highlandsniptechnology.com wrote in news: snipped-for-privacy@4ax.com:
Just use an Archimedean spiral and one can even pair up the windings if it is low voltage.
No, the largest type are 350W max, but only with a heat sink (PCB with Aluminum substrate). That one has two "planar" PCBs with the turns. The smallest 40W version has only one PCB with both primary and secondary turns. Payton calls them planar, even tho they mount above your PCB, 14mm high in the case of the 350-watt version.
-- Thanks, - Win
Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:
'Planar' in transformer nomenclature, used to refer to how the winding is arrayed. Not so much 'co-planar' to the PCB, but each turn in the same plane.
"Up to 350W planar transformers" clearly boasts the *transformers* themselves are planar, John.
Not relevant in this instance.
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Does it? The industry refers to this construction as a planar transformer. Google it.
But "boast" ? In lowercase grey type? They are, among other things, establishing a search target.
It might be to people who actually design electronics. You know, people who aren't hostile to having ideas.
I think I might try making a transmission-line transformer embedded in a multilayer PC board. They are usually a nuisance to make. I'll throw some test cases on my next multi-idea proto board.
The little Murata dc/dc converters that I like are all PCB construction, but with a ferrite toroid embedded inside the board, and windings a combination of traces and vias.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Great! I look forward to seeing the pictures in due course.
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You do need to go to a specialist printed circuit board shop if you want to do it right. It needs a lot layers of of thin substrate and some very thick copper winding tracks if you want to fill even half of the winding window with copper.
The outer layers can get by thinner copper (which does allows narrower tracks).
-- Bill Sloman, Sydney
Half!? Impossible from any fab I'm aware of. Fortunately the winding length is short and the heat transfer is good, so it's not a big deal to use high current density. 10% winding factor is good when you're talking planars, and it's really not very different from say a toroid winding, which has similar aspect ratios.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design
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Perhaps. I spent half an hour at a trade show some years ago talking to a p rinted circuit guy who specialised in the business, and a couple of years a go we had thread here about a similar sort of firm. They could get the copp er layer thicker than the substrate.
It's certainly going to worth talking to somebody like that.
-- Bill Sloman, Sydney
A buried strip-line should be non-dispersive - if you take the trouble to use a proper microwave substrate. It's not exactly an original idea.
You'd need X-rays to get a useful image.
-- Bill Sloman, Sydney
The flat turns reduce skin loss, and some air can get in there to cool the windings.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement
It's certainly going to worth talking to somebody like that.
Wonder if it's more of a potting operation than lamination -- or if the result simply has voids; give or take what spec you order?
You can of course get more copper density within a given layer, by using wide traces, but you can't fill in those gaps with regular prepreg of inferior thickness.
Typical dimensions might be, like...
2oz/layer: ~2.8 mil copper, 7-10 mil prepreg. Fills in fine. Trace width/space minimum about 7 mils (some 8 or 10, some down to 5 or 4). Meager winding factor (~15%).Heavy copper, say 12oz/layer: ~20 mil copper. 5-10 mil prepreg is just going to sit on top of it. Can't deposit copper that heavy on a flimsy core, either (so at least one dielectric layer has to be thicker). Apparently they need closer to 20 mil (as finished?) prepreg to fill in the gaps (and it's probably high-resin% prepreg at that?). Width/space about 30 mils, so you can't get many turns in a given area (should you happen to need them). Result, still a meager winding factor (~20%?).
But yeah, if someone can do thin prepreg + fill, and someone else can do vertical sidewalls (Lintek comes to mind?), the fill rate could get pretty amazing.
Actually that's even a bit concerning, simply because all the facing area (edges between adjacent turns), and the sharp corners, are going to make for wicked eddy currents / skin / proximity effect (whatever, all basically the same jumble of up-close AC effects).
I know! Bring back that laminated-wire-PCB technology and make printed litz windings! :^)
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design
At that power level it is more likely to be copper sheets, with a lacquer layer.
This datasheet for the same part, looks like copper sheets:
Cheers
Klaus
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