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New USB Specification Promises 100W of Power
Blacklaw writes "The group behind the USB 3.0 specification has announced a tweak which could lead to impressive new devices, including large-format displays, printers, and even laptops that are powered entirely from a USB port."
Awesome. I'll finally be able to implement those high powered "negative reinforcement" keyboards I keep dreaming about.
Netbook battery life drops to an average of 12 minutes.
Burns: We're building a casino!
McAllister: Arrr. Give me 5 minutes.
> laptops that are powered entirely from a USB port Finally I get to plug 2 laptops together whir their USB ports. Free perpetual energy. Problem science ?
So now, I can hook my computer to my car to jump-start it!
You know? Long ago, Apple made a display that was powered through the display cable. It worked but it was not popular in the end as they stopped doing it. So they are talking about bringing it back again?
I can see power enough to power some devices, but 100W?
You know, whatever USB standards come out, it should work equally well on a battery powered laptop and a desktop as well. People will get confused and frustrated when they buy a fancy new USB 3.0 display unit only to find they can't take it with them on the road because it doesn't work well with their laptop and the tiny travel power adapter they use while on the road.
I was hoping Power over Ethernet (PoE) was going to be successful since it would mean a LOT less cables, but this seems like a good alternative. I just hope it becomes a standard because PoE was nowhere to be found.
USB 3.0 should be less CPU intensive, because IIRC they switched from a polling protocol to an interrupt based protocol.
Who cares? If they get to the point that they can show HD video over USB 3.0 without sending all the CPU cores to 100%, then that's a win. I use a USB 2.0 / VGA adapter to increase my Work Notebook from 2 screens to 3. The USB one is usually just showing a datasheet PDF, schematic, or some other static display. Fantastic increase in capability for $50. The USB adapters have have their place, just like mobo-integrated graphics and $300 discrete cards have their place. The exciting thing is the possiblity of integrating this directly into a monitor. Have a sudden need for 6 monitors to display different power point displays at a convention? Just plug all 6 into a USB 3.0 hub attached to your notebook. That's awesome stuff. It won't replace HDMI or display port, but again, great additional functionality.
Does this mean that USB3 cannot be implemented on tablets, netbooks and other low power portables?
The current spec allows for about 4.5W (900mA at 5V). One of the last sentences in the article mentions 0.9 Watts.
Now, I could totally understand this kind of mistake in the past. But don't these people understand the wonder that is Google? Before I made this post, I wanted to make sure that I wasn't the dufus, and typed 900mA * 5V into Google. It's not that hard to fact check, is it?
"I will trust Google to 'do no evil' until the founders no longer run it." Hello Alphabet.
Even with USB2, there was the persistent problem that certain applications(notably 2.5 inch external drives) were right on the edge of what the spec allowed. Some machines played fast and loose, and everything worked fine, some played to spec, and the device wouldn't spin up, or the bus would freak out, or whatever. Despite USB's formalized, standardized, power-request mechanism(100ma on connect, negotiate in units of 100ma for up to 400 more...), the, er... 'inventive'... nature of the peripheral ecosystem always created some uncertainty: Some devices just requested 500ma at all times, to avoid possible brownouts, leading to more spec-compliant busses freaking out about lack of power even when actual draw was well within safe limits, some devices (fans, LED goosenecks, humping dogs) just grabbed the +5 and ground rails and hoped for the best, without any negotiations. Some hubs report themselves as self-powered(and thus good for 500ma per-port) even when they were bus powered(and thus only good for 400ma across however many ports they had). Some others were self-powered; but with wall-warts that could only deliver 500ma to a number of ports smaller than the number available(7-port hubs with 1amp adapters, I'm looking at you...)
This new standard seems like it would simply be a polite codification of this confusion. Particularly at low voltage, 100watts is nontrivial current(and nontrivial power generally, most non-DTR laptop bricks are less than that...) Many PCB layouts would burn a trace trying to deliver that, and you can bet that your garden-variety 10-USB-ports boring desktop isn't going to ship with 1000watts of PSU headroom...
This will mean that, in effect, devices will be able to demand up to 100 watts in a 'compliant' way; but the capabilities of USB ports on the market will vary enormously by device. A laptop with an 85 watt power brick is hardly going to be good for 100watts out of a port. Worse, it might be good for 50 when lightly loaded and fully charged; but only 5 when charging its battery and flogging its CPU... Having a device that only intermittently functions is near worthless, even if it is all entirely standard... A desktop might ship with the ability to push a single port to 100; but then it will either have to beef up its traces significantly, or have the always-confusing-to-dumb-users-and-people-fumbling-behind-desks '1 special blessed "high power" port, and 9 identical-feeling-but-low-power ones' configuration. Fan-fucking-tastic...
While a bit more power on the bus certainly would expand the number of viable, bus-powered use cases, I'm just not sure that such a high 'standard' number can ever be usefully 'standard'. Hooray, it is now officially standard for specialized devices to shove 100watts across a USB bus. Doesn't change the fact that it won't work in 90+% of ports, and will probably burn a fair percentage of cheaper cables. Unless they come up with some sensible set of "tiers", so that people actually know what works with what, this seems like it is going to end in a mess of nominally-USB powered docking stations with wall warts and mini-B connectors, at best.
While its comparative obscurity, and the general lack of bus-powered devices made it less of an issue, Firewire flirted with this problem in its early days: Both available power and available voltage on a given 6-pin port were widely variable: A desktop could, if it so chose, be pumping out 24 volts and reasonably credible wattage. One of the(almost exclusively Apple) laptops with a 6-pin port might be limited to a handful of watts at whatever voltage its battery was set to provide. In practice, much firewire gear just skipped bus power entirely(despite the fact that charging over firewire would have been a very popular consumer camcorder feature, if today's flip-likes are anything to go by), the mixture of widely variable power availability, and the 'i.link' or just 'IEEE1394' connectors entirely without bus power pretty much doomed the widespread availability of bus-powered peripherals. USB's pitiful 2.5watts was rather limiting; but at least you could reasonably assume that it would be there...
I'm looking forward to the USB-powered space heaters that office secretaries will put under their desks. They were forbidden from doing that before because it takes too much power from the wall plugs, but this comes from the COMPUTER so it must be okay!
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
At higher speeds the OS stuff starts going back to polling to be less CPU intensive :).
http://en.wikipedia.org/wiki/New_API
As several people have pointed out, 100W seems like too much. I bet this is just a specification tweak to provide headroom for devices that need more than 4.5W (like 8W or 10W or 15W). In other words, the spec is no longer an artificial limit on how much power you can provide.
Visit the
Firewire
Thunderbolt is Intel's technology.
Don't let facts get in the way of good Apple bash though.
I'm thinking of attaching my friggin' laser mouse onto a sharks head when USB3 comes out.
"That's the way to do it" - Punch
USB 2: 480 Mb/sec theoretical, real world half that
USB 3: 5 Gb/sec theoretical, real world about 3.2 Gb/sec
DVI: 4 Gb/sec single link, need dual-link for more than 1900x1200 resolution
DisplayPort: 1.6 to 5.4 Gb/sec per lane, four lanes, for 17.3 Gb/sec max, real world is 80% of that (enough for four 1080p60 displays), plus a 1 Mb/sec auxiliary channel.
Thunderbolt: 20 Gb/sec bi-directional, can carry the four lanes of DisplayPort data with room to spare.
So you have less bandwidth than a single-link DVI and far less than the modern competition. Your monitors had better be low-res, even for USB 3.