VHF Laptop Power Supply (DART)

[polar8]

Ok, so it's not on Kickstarter yet (company predicts this spring) but it was recently launched at CES and has been getting lots of press. Thoughts?

http://www.finsix.com/index.html

[tom66]

Technical information:
http://www.finsix.com/files/FINsix_Tech.pdf

It sounds like they've basically taken the SMPS and kicked it into the tens of MHz range. I would have thought power transistor losses at that point would not make it worth it but apparently not,  as they address that.

If they can make it practical and cheap enough it looks like it could be quite a winner, though I doubt we will see converters like this on the average PCB, must be using RF capable PCB with known impedances etc. Maybe could work for laptop/computer motherboards though as they already need controlled impedance for RAM, PCI, etc.

[AG6QR]

I wonder about the RF implications of this.  It says that it meets applicable standards for conducted and radiated EMI, but that's not a guarantee of problem-free operation, especially for those of us who like to play with radios.

However, it might be good news.  By shifting into VHF, they'll be above the most interesting frequencies for us ham radio operators.  The range from roughly 1.6MHz to roughly 30MHz is where weak signals can most easily bounce around the world via the ionosphere.  A lot of switching power supplies pollute this range, largely with harmonics that produce broad-spectrum hash across the shortwave bands.  I'd love to see the switching power supplies move above this area.  The higher frequencies are normally of use mostly for short range communications anyway, and they tend to be less susceptible to interference.  But they're not entirely immune...

They're talking about switching frequencies in the range of 30MHz to 100MHz, and I'd assume that harmonics would extend much higher.  That 30-100MHz range covers some land mobile and police radios, plus part of the FM broadcast band.  Harmonics might extend into aircraft navigation and voice communications, terrestrial TV, and other services at higher frequencies.

If this works, I think it'll catch on big time, and eventually be copied by many.  The advantages sound too good to pass up.

[Rufus]

Ok, so it's not on Kickstarter yet (company predicts this spring) but it was recently launched at CES and has been getting lots of press. Thoughts?

http://www.finsix.com/index.html

Intel's switch mode regulators integrated in the die of Haswell processors are even more ridiculously small, high power, and high frequency.

Not sure how easy it is to get extremely high efficiency which is required to manage heat in the small packages or how economical it is.

Strange they seem to be only offering product to end users who are going to have to throw away a PSU they already have. You would think there would be plenty of interest and more business for them from OEMs so maybe it is too expensive (except for apple customers who will pay a large premium for anything, but, I'm sure apple could do this themselves and probably will if it is practical).

[tom66]

I'm going to guess the first generation of this product will cost at least $100. I don't see RF power transistors being cheap especially if rated for 500V. Probably too expensive for laptop OEMs to include by default, but could be an option that's available for purchase at the same time.

If finsix have patents on it, then they might license the technology to Apple, or make power supplies to Apple's requirements.

How do you rectify the output of a 30MHz SMPS? What kind of efficiency will these have? Will the output be cleaner, given the lower filter requirements? Will they be repairable?

[vk6zgo]

I wonder about the RF implications of this.  It says that it meets applicable standards for conducted and radiated EMI, but that's not a guarantee of problem-free operation, especially for those of us who like to play with radios.

However, it might be good news.  By shifting into VHF, they'll be above the most interesting frequencies for us ham radio operators.  The range from roughly 1.6MHz to roughly 30MHz is where weak signals can most easily bounce around the world via the ionosphere.  A lot of switching power supplies pollute this range, largely with harmonics that produce broad-spectrum hash across the shortwave bands.  I'd love to see the switching power supplies move above this area.  The higher frequencies are normally of use mostly for short range communications anyway, and they tend to be less susceptible to interference.  But they're not entirely immune...

They're talking about switching frequencies in the range of 30MHz to 100MHz, and I'd assume that harmonics would extend much higher.  That 30-100MHz range covers some land mobile and police radios, plus part of the FM broadcast band.  Harmonics might extend into aircraft navigation and voice communications, terrestrial TV, and other services at higher frequencies.

If this works, I think it'll catch on big time, and eventually be copied by many.  The advantages sound too good to pass up.

6 metres, 2metres,& 70cm all are bastions of weak signal work.
If it goes from 30MHz to 100MHz,it covers 6m directly,& probably 2m & 70cm on harmonics.

6m can hardly be regarded as "short range".
It's not a matter of noise propagated from far away,it's the guy next door!

[Marco]

An old paper describing the technology they used (more detailed than their website) : "A Very High Frequency dc-dc Converter Based on a Class ?2 Resonant Inverter".

[tom66]

If it's as described in that paper, it's of a nonisolated topology which surely means it cannot be used for mains power.

[ConKbot]

I'm going to guess the first generation of this product will cost at least $100. I don't see RF power transistors being cheap especially if rated for 500V. Probably too expensive for laptop OEMs to include by default, but could be an option that's available for purchase at the same time.

If finsix have patents on it, then they might license the technology to Apple, or make power supplies to Apple's requirements.

How do you rectify the output of a 30MHz SMPS? What kind of efficiency will these have? Will the output be cleaner, given the lower filter requirements? Will they be repairable?

The same way you switch it If youre getting into efficient SMPS's synchronous rectification is almost a given.

[Rasz]

I dont get it, what are the advantages?
I seem to remember Satellites use SMPSes in MHz region to make them small and light. But my laptop bag is not a satellite launching rocket, I wont die if my PSU is 10cm instead of 4cm.

[AdShea]

A few guys in my lab are working on stuff like this. They're much cleaner than normal hard-switched supplies because they're closer to RF circuitry (Class E into a rectifier) and don't really have as many harmonics in the system.

As for losses, they're horrible for losses for the amount of Si they use, but generally you can get away with buying more power switch (to reduce those losses) if you are able to make up the cost/space/losses in the passives. The big win here is that you can drop volume with about the square of operating frequency up to a few MHz then about proportional to frequency above that.

As for use, most laptop supplies aren't too awful, but I'd sure like something smaller than they paperback-sized brick that comes with my W520. A beefy i7 and high-end Quadro card sucks down a fair bit of power.

[Harvs]

I dont get it, what are the advantages?

I have a 13" ultrabook that I cart everywhere with me, and I know many others that do the same.  It's only slightly larger than then screen size, and about 1.5 samsung galaxies thick.  Yet the power adapter is the same sort of size as most other 60W laptop power adapters, read huge in relation to the device.  Ultrabooks are a premium product that's relatively expensive and bought by a lot of professionals that travel, if there was a product on the shelf today for $100 that was a third the size of the current power adapter for these I reckon they'd fly off the shelf.

[Corporate666]

Curious what those more knowledgeable think about this.  They are basically using very high frequency switching in an SMPS to get everything smaller, ultimately fitting 65W worth of power supply into a very small plug-in adapter.

https://www.kickstarter.com/projects/215201435/dart-the-worlds-smallest-laptop-adapter

I am not qualified to know what the shortcomings of such a design are, but off the top of my head I wonder about switching losses, as well as thinking "if it was just as simple as cranking up the frequency, it would have been done lots of times before".

So I am real interested in what the folks here think about this project....

[mariush]

Discussed here: https://www.eevblog.com/forum/crowd-funded-projects/vhf-laptop-power-supply/

[johansen]

i bought a 90 watt adapter off ebay for 9$ iirc.

then promptly broke it by removing the resistor divider and turning it on... thinking it wouldn't nuke itself. i think i saw 27 volts on the output for a moment.no emi flter, just a fwb into a 400 volt capacitor, then a flyback converter, regulated through an optical isolator.

of course, the thought concerns me.. for a laptop, you don't really need clean power going in. why not do away with the output filtering completely and run 120 hz or 100 hz ripple all the way to 50% or whatever it is.. no LF input or output filtering needed.
you could even incorporate pfc into the flyback converter with nothing but a .1uF on the input and a 10uF ceramic on the output.

in fact i'm fairly certain i could get one 4th the normal volume and 1/6th the normal weight for 60-150 watt adapters at just 500khz and standard semi resonant topology, including pfc input. but it would cost more than its worth.

[Corporate666]

Discussed here: https://www.eevblog.com/forum/crowd-funded-projects/vhf-laptop-power-supply/

Thank you!  Maybe a moderator can merge threads?  I completely missed the other thread.

[mikeselectricstuff]

I think a big potential space-saving trick has been missed for decades.
A significant space-hog in any SMPS is the input reservoir capacitor, however for a device that is used for charging a battery, there is no fundamental need to supply continuous DC.
If the charging circuitry was designed to accept a 100/120Hz pulsed supply, then it would be possible to use a PSU with minimal smoothing, and eliminate the capacitor.
It would also eliminate the need for a seperate power-factor correction converter.

[peter.mitchell]

I think a big potential space-saving trick has been missed for decades.
A significant space-hog in any SMPS is the input reservoir capacitor, however for a device that is used for charging a battery, there is no fundamental need to supply continuous DC.
If the charging circuitry was designed to accept a 100/120Hz pulsed supply, then it would be possible to use a PSU with minimal smoothing, and eliminate the capacitor.
It would also eliminate the need for a seperate power-factor correction converter.

Indeed.
Another method though could be adding additional windings to the SMPS and an additional switch and rely on the output capacitors, I mean, the difference between input and output is so high that an unfiltered 240v AC sine has a differential above 20v for 95%~ of the time...

[theatrus]

https://www.kickstarter.com/projects/215201435/dart-the-worlds-smallest-laptop-adapter?ref=search

Something tells me this is going to be a bear to get through any certification process. And apparently MIT has a patent on the VHF band.

[mariush]

Apparently people DON'T KNOW HOW TO USE THE SEARCH BUTTON :  https://www.eevblog.com/forum/crowd-funded-projects/vhf-laptop-power-supply/

mod ... maybe add DART in the name of that thread so this won't happen so often ?

And some people don't know how to use the Report to Moderator button  . It's the best way to bring something like this to the attention of a moderator.

[tom66]

I think a big potential space-saving trick has been missed for decades.
A significant space-hog in any SMPS is the input reservoir capacitor, however for a device that is used for charging a battery, there is no fundamental need to supply continuous DC.
If the charging circuitry was designed to accept a 100/120Hz pulsed supply, then it would be possible to use a PSU with minimal smoothing, and eliminate the capacitor.
It would also eliminate the need for a seperate power-factor correction converter.

But a laptop's processor -does- need constant DC. How would you supply that? Most laptops switch all busses to AC power only once it's available. Plus you don't want to be shoving 100Hz/120Hz ripple through a small output capacitor.

[mikeselectricstuff]

I think a big potential space-saving trick has been missed for decades.
A significant space-hog in any SMPS is the input reservoir capacitor, however for a device that is used for charging a battery, there is no fundamental need to supply continuous DC.
If the charging circuitry was designed to accept a 100/120Hz pulsed supply, then it would be possible to use a PSU with minimal smoothing, and eliminate the capacitor.
It would also eliminate the need for a seperate power-factor correction converter.

But a laptop's processor -does- need constant DC. How would you supply that?

From the  battery, obviously.

[Marco]

Would using the battery as a smoothing capacitor not quickly destroy it?

[scientist]

These twats seriously think patents don't apply to them?

[suicidaleggroll]

These twats seriously think patents don't apply to them?

They own the patent mentioned in the description...or are you referring to something else?