No? How about a dab of epoxy to a copper pour, with thermal vias to a ground plane? That's got to reduce theta by some number of times. The layout needs to suck heat from the lead connections, too. Clever layer interleaves and such.
Easy enough to try. One copper winding makes a damned fine RTD.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
This board is a very dense one with several power converters on it. So I made it have a good "heat-sucking" core and a cooling strip on the side which is at the same time the mounting strip. Tons of vias. And this inductor is located right at the thermal strip for cooling reasons. Epoxy is one option but I am thinking more about thermally conductive pliable plastics to sink heat away by pressing agains a metal surface. Can't remember the name, have to dig it out.
However, first I want to push these losses down. Because burning several watts in the inductor isn't a good thing in the first place, it dings us on efficiency. Plus heat sinking has its limits if the enclosure is small. The whole box will eventually become a hot-plate.
-- Regards, Joerg http://www.analogconsultants.com/
Well, now we know it is core loss. We have received the shipment with higher inductance, which of course comes at the price of higher DC resistance and higher copper losses. Result -> lower temperatures. We'll have to see where the sweet spot is and that can only be found out experimentally because no reliable data is available about core loss.
-- Regards, Joerg http://www.analogconsultants.com/
Laird and Bergquist make thermal transfer stuff, limp and sticky and about the look and feel of used chewing gum. Thetas are in the 1-5 w/m-k sort of range. You could put a patch of that on the bottom of an inductor and squish it down before reflow.
We just Gerbered our 2-cubic-inch, 5 kilowatt laser driver. That wasn't too bad thermally, because the expected pulse rate is low. It does use the schmitt-trigger boost-doubler converter to charge the caps, with a single tiny Coilcraft inductor. So I have a SOT23 fet in the boost power supply and a TO247 in the laser driver stage.
I just got the first bare boards on a 300 amp driver, where thermals matter. These ROHS gold boards are gorgeous.
The D2PAK power fets are on the opposite side. Thermal vias and interleaved planes transport heat to the big gold pad, which can be bolted to a heatsink block between the board and a baseplate.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Indeed, didn't know Laird had it:
Kinda pricey though.
Nice. Are you going to solder it lead-free? I try to avoid that wherever I can.
That's just about how I did it on our board, except that we use bigger mounting screws because ours goes into rough environments.
-- Regards, Joerg http://www.analogconsultants.com/
I think you are more of a brick layer than an architect.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
My engineering boards will be 63/37 solder, but lately we are doing more and more ROHS stuff. Ugly solder joints. We do now buy all boards with gold over nickel so we have to option to build ROHS. Nearly all our parts in stock are ROHS now, too.
I can't keep engineering boards around. Somebody always ships them as demos, or sells them. I should disfigure them.
The heatsink block screw holes are right in the middle of the 300 amp current flow, so I kept the holes small. There's no annular ring on the top side so we'll use insulating washers under the screw heads.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
I think this fits you to a tee...
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
And you evaded the actual question...
"I do think my hold-off-time method is unique. Have you deduced how the other hold-off-time input works yet?"
I await your explanation... otherwise everyone will think that you're just the hod carrier >:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Quit being coy. If you have something useful to say, say it.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Struggling to avoid answering such a simple question? ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Another argument for finding your own ferrite core and winding your own coi ls - or in this day and age, buying a core pair intended for use with print ed windings, and getting your own windings printed, though probably not on the same circuit board as you use for the rest of the circuit, since gettin g a decent copper fill factor depends on putting very thick layers of coppe r on very thin substrates in a multilayer board.
-- Bill Sloman, Sydney
A noble idea, but planar magnetics take up an awful lot of board area.
I suppose if one were to crank up the board layers, components could be placed on the outer surfaces while routing the windings through inner layers between. Keep low voltages away (current sense and the like). Might be tolerable that way, but still, lots of area, and copper losses are intrinsically worse due to the poorer fill factor.
Tim
-- Deep Friar: a very philos> > > > Download the Epcos tool and try different operating points:
Another argument for finding your own ferrite core and winding your own coils - or in this day and age, buying a core pair intended for use with printed windings, and getting your own windings printed, though probably not on the same circuit board as you use for the rest of the circuit, since getting a decent copper fill factor depends on putting very thick layers of copper on very thin substrates in a multilayer board.
-- Bill Sloman, Sydney
Which is why I explicitly rejected putting the winding on the same board as the rest of the circuit.
The fill factor for round copper wires isn't 100% - closer to 70% IIRR - an d some board manufacturers can put down copper layers that are thicker than than board material, so you can probably get pretty close to round wire co pper fill factors, and - in theory - might even be able to do a bit better. But it would take a specialist printed circuit board manufacturer to get y ou there.
-- Bill Sloman, Sydney
I'm not going to fist-fight you, or road-race you, or engage in a gun battle, or spend any time analyzing the nooks and crannies of that hairball.
If you want to share ideas with the group, do it. If you want to be a pathetic old git over a 40 year old circuit that probably never worked, play with yourself.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
That "hairball" was a manufactured chip. Worked exactly as designed, thank you. (No CAD, it was bread-boarded :)
All functions are marked on the schematic. I guess it's too complicated for you to follow. Proves my observation that you "design" by copying AppNotes. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Try the Murata A series
The graph shows about 15C above ambient for 7A and 10uH.
If it was a chip, give us a link to the data sheet.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
I can't, I need a dual inductor.
They all show that kind of stuff but it is deceiving. It does not take into account core losses and those are the lion's share in many switcher designs.
-- Regards, Joerg http://www.analogconsultants.com/
95% of my chip designs are custom private label. (And you know that. You're just throwing your usual sand in the air.) This chip was for Integrated Technology Corp...
Call Rod and ask him if there was a data sheet. I really have no idea if it was sold individually... most likely sold only within their instruments. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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