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new 30MHz to 300MHz switcher - worlds smallest laptop adapter

Discussion in 'Electronic Design' started by Jamie M, Dec 25, 2013.

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  1. Jamie M

    Jamie M Guest

    Hi,

    Here's a new SMPS switcher apparently coming out next year for laptops:

    http://phys.org/news/2013-12-circuit-laptop-charger-brick.html

    It apparently has a "power reclaiming scheme" for higher efficiency,
    would this be conventional sync rectification or some other thing?

    It looks like power electronics is in for a big (r)evolution once the
    300MHz+ designs start to spread!

    cheers,
    Jamie
     
  2. There are "universal" converters, that apparently more-or-less work
    fairly well.
    Not sure that follows.
    You could try crowdfunding if you were interested. Those bricks are a
    real PITA. A lot of people would shell out $50 or $100 if it made the
    problem disappear. It wouldn't have to be revolutionary technology,
    just a different trade-off (and probably some kick-ass styling and
    slick videography/photography to sell it).


    Best regards,
    Spehro Pefhany
     
  3. Artem

    Artem Guest

    Ordinary MOSFET at 300 Mhz?
     
  4. Artem

    Artem Guest

    RF transistors usually low voltages.
     
  5. Artem

    Artem Guest

    1. It's only for 110v power grid.
    2. Bandwidth TV only 6.5 Mhz.
    3. Efficiency will be low because transistor in linear mode.
     
  6. Artem

    Artem Guest


    Yes. And main benefit of resonant converter is decreasing switching losses by switching when current is minimum.
    For linear amplifier theoretical efficiency only 78.5%
    http://en.wikipedia.org/wiki/Amplifier#Class_B
     
  7. Guest

    However annoying patents are, these things are always patented, and
    have to be. These guys filed in 2009. Without patents it wouldn't
    make sense to do all that work--make all that investment--only
    to have it ripped off the nanosecond you ship.

    The front end is a capacitive charge pump that charges many capacitors
    and switches in series, then flips another set of switches to
    discharge the caps in parallel, creating a raw output. A
    synchronous buck efficiently regulates the rough voltage
    thus created down to the desired output.

    It runs the switches and caps at HV in series, so only low
    voltage switches are needed. Ditto for the finishing regulator.

    http://patft.uspto.gov/netacgi/nph-...50&s1=8212541.PN.&OS=PN/8212541&RS=PN/8212541

    The main inventive notion here seems to have been getting the operations
    within the range of fast, low-voltage elements.

    I haven't looked at it in depth yet..time for Christmas!

    Cheers,
    James Arthur
     
  8. GaN technology is about ready. Even the drivers are off-the-shelf.


    Best regards,
    Spehro Pefhany
     
  9. According to a presentation I saw on licensed inventions from another
    university (Kirsten Leute @ Stanford), they've taken in 1.6bn in
    licensing fees since 1971 and get disclosures at higher than a daily
    basis, and _start_ patent applications on ~50% but they have not had a
    new high-income winner in about 18 years. The last big one was
    Google-related (1996 $337m as of 2012- they took some equity which
    paid off big)... but mostly life sciences/biotech stuff with a couuple
    of communications/EE inventions. Before 1996 it was every 2-3 years
    between big hits.

    I guess one could speculate on whether the pace of home-run inventions
    has actually slowed down, or something else is going on.


    Best regards,
    Spehro Pefhany
     
  10. Guest

    It's my impression that either from conviction or
    poor risk/reward conditions, there is less inventing
    in the US.
    People are spending time mitigating risk and cost,
    not seeking it.

    OTOH, there's all sorts of opportunity for inventions
    and synergy--cheap wireless, FLASH, GHz CPU, etc.

    Cheers,
    James Arthur
     
  11. Guest

    Okay, I looked at it a little deeper.

    I missed on a couple points.

    First, the switched capacitor switches aren't low voltage. There
    are only a few of them, so that doesn't fly. Also, when S1 of
    Fig. 6 is open, one of the switches S2 has to stand off the entire
    input voltage. Let's hope S2 never pops!

    Second, I figured out the "energy recirculation" -- it's kind
    of elegant. The charge pump efficiency is improved by charging
    the series capacitor string *through the synchronous buck*.
    That way, the series capacitor strings' peak charge current is
    controlled, avoiding inrush charging losses. That's clever.

    In effect, the buck runs off the switched-cap converter's ripple
    voltage when the cap string is in series, and off the charge
    pump caps in parallel during the paralleled time.

    It also means you don't need nearly as many switched-cap stages
    to get to the roughed output used to feed the sync. buck.

    The VHF aspect is confined to the synch. buck finishing regulator.
    Its low input voltage allows the use of fast, small geometry
    devices.

    There, I think that's the gist of it.

    No galvanic isolation, which might be changed by substitution of
    a suitable isolated "buck."

    Cheers,
    James Arthur
     
  12. Exactly, nothing new here, just some one trying to bank on
    old tech..

    Jamie
     
  13. Guest

    You need the cap-switch network. The low input voltage into the
    synch. buck is what produces the other opportunities:
    1. the cap-switching reverse Marx generator (thanks Jon!)
    makes a low, unregulated voltage pretty efficiently.
    2. The synchronous buck can use low-voltage, low resistance,
    low Qc FETs that scream.

    The patent suggests running the cap-switcher at, say, 1Mhz, and
    the synch. buck at 5-100x that.

    Ramifications: the low voltage differential into the buck
    increases the buck's duty cycle, which increases efficiency.
    Low voltage differential also reduces the inductance needed
    for a given ripple current, which increases efficiency,
    reduces volume, and reduces copper losses, which reduces volume
    even more.

    There's usually a fatal flaw. Haven't seen it yet, but it looks
    fragile--lots of switches have to flip reliably, or you smoke it.

    Cheers,
    James Arthur
     
  14. Guest

    I haven't seen the soft-charging of a cap-switcher trick. Nor
    have I seen using a cap-switcher front-end to a buck switcher,
    or that people recognized the advantages that flow from that.

    I'm not endorsing it mind you, just analyzing.

    Cheers,
    James Arthur
    (P.S. I've not seen soft-charging in a Marx generator either--
    that's a good idea :)
     
  15. Guest

    Agreed--any cap mismatch produces dV(c), making spikey spikes when
    switching from series to parallel configuration, same as a
    conventional charge-pump.
    I haven't bothered with any numbers, but I rather doubt they could
    use on-chip caps. The capacitances and voltages needed are too high.
    So says my gut, anyhow.

    Let's see...if we wanted 60w (input) worth of charge packets at
    1MHz at 170VDC input,
    c=60W/(.5*v^2*1Mhz)= 4nF for the series string, or 12nF each for
    a string of 3, at 57 volts each.

    That would be quite a chip.
    Cheers,
    James Arthur
     
  16. Guest

    Of course, we all know that. But I haven't seen the bottom of a
    series'd string of switched caps terminated in a synchronous
    buck, specifically to reduce losses in the switch-cap charging
    and provide a low input voltage to the buck.

    You may think it's obvious but the obvious rejoinder is that if
    a. it's better, and
    b. obvious,
    why have billions of laptop adapters been made, without ever
    using it?
    If you were the first one to do it, and no one else had thought of
    it, that might be patentable too. In 1930. :)
    If it's normal practice, can you point to anyone anywhere that's done it?
    I can't.

    Right, but you're missing the point. He can generate, say, +5v from
    +170v with the switched cap thing, so that the switcher can be a
    30MHz unit with 10v mosfets. Or +3v and 5v mosfets, etc.
    The existing selection of laptop adapters, representing millions
    of man-hours of design, suggest that no one else came up with it.
    That's the whole point.
    That could very well be. If the thing doesn't deliver, they're
    screwed. But if they've worked out any defects, it could be a
    home-run.

    It's reasonable to be skeptical, until then.

    Cheers,
    James Arthur
     
  17. Guest

    The legalese annoys me, but I skimmed the claims. They all 'recite'
    (that's the term of art) a switched-cap front end with a dynamically
    alterable division ratio, coupled with a conventional switcher that
    advantageously uses the lowered input voltage, and produces a regulated
    output.

    Seems fair to me, and pretty specific.

    Not, not that--have you seen anyone using an adaptible-ratio
    switched-cap as a front-end to a low-voltage switcher?
    He actually does coarse regulation by changing the cap-switching
    ratios. I skipped that as not very interesting.
    I didn't see any efficiency numbers either, but one infers high efficiency
    from the small form factor, otherwise it'd burn up.
    Sounds good.

    Cheers,
    James Arthur
     
  18. Peter

    Peter Guest

    Guys, is it physically possible to transfer energy with just
    capacitors for isolation?

    I know you can send data that way (because it can be encoded with just
    edges, and providing there isn't too much common mode noise, the edges
    can be decoded) but I can't see any way to transfer *power* that way.

    Inductive components are needed if you want isolation - as in most
    consumer appliances.

    LED lamps don't need isolation and there is a huge amount of work
    being done in that area.
     
  19. Tim Williams

    Tim Williams Guest

    Signals anyway,
    http://www.ti.com/lit/ds/symlink/iso103.pdf

    Nothing wrong with it for power, but the capacitances will be small to
    ensure galvanic isolation (~nF), suggesting very high frequencies or
    inductive reactances to cancel it. The inductive case looks like coupled
    resonators, which might be achieved accidentally by proximity of the coils
    (in which case you have "wireless energy", which is a slowly rising fad
    these days). At that point, isolation distance is only a matter of having
    sufficiently high Q factors (and closely matched resonators).

    Tim
     
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