USB 3.0 Power Delivery Specification - Page 1
Forum section: electronics / general

author: Psi
author_rank: Super Contributor
timestamp: July 24, 2012, 11:38:26 am
content: http://www.techweekeurope.co.uk/news/usb-3-0-power-delivery-charging-86983I'll copy the interesting details in case you don't want to read it.Quote100W seems kinda insane to me, but if we get ultra fast charge batteries in our phones then it maybe needed.One thing that worries me is viruses destroying your hardware or starting fires by compromising the USB subsystem and forcing the port to 20V when the device expects 5V

author: digsys
author_rank: Unknown
timestamp: July 24, 2012, 11:56:40 am
content: QuoteBetter start adding a polyfuse + transorb to all USB inputs I guess !! No doubt there'll be a few tears until everyone finds out

author: Psi
author_rank: Super Contributor
timestamp: July 24, 2012, 11:59:33 am
content: As long as the voltage request and switching is done entirely in hardware it should be ok

author: Things
author_rank: Regular Contributor
timestamp: July 24, 2012, 12:00:42 pm
content: It'd make sense to me that the only thing that could change the USB voltage would be the device itself, and the change would be done in hardware rather than software (Although probably still in software, but using a uC or other device not part of the main processor)

author: _Sin
author_rank: Regular Contributor
timestamp: July 24, 2012, 12:12:56 pm
content: Ah, this will usher in a new age of pointless USB "peripherals".Having said that... mini USB reflow oven anyone?

author: Psi
author_rank: Super Contributor
timestamp: July 24, 2012, 12:19:20 pm
content: With 100W (20V @ 5A) you could drop the custom AC adapter and charge over USB instead.Which introduces some interesting ideas... Like charging one laptop from another, or the ever so popular energy black hole when you charge a laptop from itself with a loop cable

author: _Sin
author_rank: Regular Contributor
timestamp: July 24, 2012, 12:23:44 pm
content: USB soldering iron, just in case I need to repair something while travelling. Like the laptop!

author: Rerouter
author_rank: Super Contributor
timestamp: July 24, 2012, 12:25:09 pm
content: actually psi that is something i have to wonder about, would anyone ever think that far ahead to actually prevent a device that is both powered by and supports usb to not stupidly drain itself from a power loop like that :/

author: Psi
author_rank: Super Contributor
timestamp: July 24, 2012, 12:32:52 pm
content: Doubtful, if someone wants to run their laptop flat quicker who are we to argue with them

author: T4P
author_rank: Super Contributor
timestamp: July 24, 2012, 12:58:54 pm
content: Special cables ...Go on, i want to see people using AWG 24 wires( That's like the largest they use now )

author: madires
author_rank: Super Contributor
timestamp: July 24, 2012, 08:46:53 pm
content: Will we see standalone USB power supplies? Or does my PC power supply need to provide +100W for each USB port? 10 USB ports = 1000W? Doesn't make much sense. Maybe just two 100W USB ports?

author: tom66
author_rank: Super Contributor
timestamp: July 24, 2012, 08:59:27 pm
content: Why 20V, and not something like 24V or 42V? Both have readily available DC-DC converters. Or, same voltage as POE, 48V DC. Keep it simple...

author: Sionyn
author_rank: Frequent Contributor
timestamp: July 24, 2012, 09:05:14 pm
content: its understandable ive never like usb device that use usb to suck power like fans hovers etc

author: mariush
author_rank: Super Contributor
timestamp: July 24, 2012, 11:07:23 pm
content: ... and just as everyone designs power supplies with dc-dc regulators for 3.3v and 5v inside that can only do 20-25a max, they have to come up with 5v@2a for each port...... and why the hell would you add 20v, how did the reason selecting this voltage? Compatibility with laptop chargers? Why not 24?Well, I guess devices won't really all use 2A on each port but still...In an ideal world I would like to see pc power supplies that would deliver just 12v and possibly 5v to the computer and get rid of the 3.3v rails... seems like only mSATA and 1.8" ssd drivers currently use it. Some motherboards use it with a dc-dc converter to power the ram slots but that's about it as far as I know.Anyway, I just can't picture 100w on usb ports in the back of a motherboard... wonder if there's gonna be ANOTHER 8pin connector there just for usb.

author: tom66
author_rank: Super Contributor
timestamp: July 24, 2012, 11:20:04 pm
content: My idea would be to ditch the 5V, 12V, everything, and replace it with a single 3.3V or 5V AUX (standby rail @ 3A max) and a relatively unregulated 30 to 42V DC rail. Reasoning behind this is 30-42V is within the range of a lot of 42V DC-DCs so there's existing parts base, it's reasonably safe (can't shock yourself on 42V, it might tingle a bit but that's it) and being tolerant of unregulated supplies means you can directly power the PC from a 10 cell lipoly pack or an 18 cell (3x12V) lead acid battery. Also you wouldn't need a ridiculous 80A on 12V for 1kW, but a more sane ~35A. In the ideal design, the aux rail would be optional, and if it is not present, the motherboard provides the aux power from the main power, otherwise the aux power is used to run standby functions and turn on/off the main rail.The only things that really care about regulation are fans and motors, so there'd either need to be speed regulation on each or a 12V DC-DC on the motherboard.It could also be practical to power computers off a central DC supply, but it would be more likely to be 300V+... I believe some server rooms are doing this now. Obviously you don't want 300V in your computer.

author: mariush
author_rank: Super Contributor
timestamp: July 25, 2012, 12:39:34 am
content: The reason why I said 5v and 12v is simply for compatibility with all the devices that already exist out there. I would ditch the 5v as well and keep only 12v but there's too many devices out there using 5v...I would think 3.3v is too low, the voltage drop on the cables would be big if the cables are long, you would probably need voltage feedback from the power supply to adjust for the losses. 12v is reasonable.The Open Compute guys (facebook's open source hardware initiative) seem to have about the same idea:http://opencompute.org/projects/power-supply/They're designing the servers to work on 12.5v dc and their power supplies as you can see in the link above accept 277v AC (+/-10%) or 48V DC nominal...though they say it's backup power, connected to a 54v battery bank.

author: T4P
author_rank: Super Contributor
timestamp: July 25, 2012, 02:31:08 am
content: Quote from: madires on July 24, 2012, 08:46:53 pmSpecial USB 3 ports, not just normal usb ports.

author: T4P
author_rank: Super Contributor
timestamp: July 25, 2012, 02:39:55 am
content: ATX Standard was formed so damn long ago, stop complainingQuote from: mariush on July 24, 2012, 11:07:23 pmKeep all the rails, there's really not going to have a point to throw away all the current voltages, as +12/-12v +5V +3.3V is the most efficient and best tradeoff between cost and complexityImagine more DC-DC converters, 3.3V provides power for the 2.5V references on boardhttp://en.wikipedia.org/wiki/Molex_connector#Motherboard_power_connector_.28Molex_Mini-fit_Jr..29Try developing a buck converter that is 42V-sub 2V.

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2012, 04:59:47 am
content: They're going to need a socket colour system to denote the max power profile which a USB3 port supports.Otherwise it's going to be impossible to know which port supports a device without trying it.

author: Unknown
author_rank: Unknown
timestamp: July 25, 2012, 05:18:45 am
content: Google engineers proposed deleting all voltages from the power supplies except +12V. Their rationale being that boards have their own voltage regulators anyway so eliminating unnecessary rails would make computers cheaper and more energy efficient. According to them 30 to 40% of the consumed power is wasted for voltage conversion.services.google.com/blog_resources/PSU_white_paper.pdfUSB folks have a lesson to learn from that.

author: T4P
author_rank: Super Contributor
timestamp: July 25, 2012, 10:27:46 am
content: Quote from: HAL-42b on July 25, 2012, 05:18:45 amSorry i mean, 12V-5V is pointless. It creates more waste heat for the harddisks

author: tom66
author_rank: Super Contributor
timestamp: July 25, 2012, 12:20:18 pm
content: Quote from: DaveXRT on July 25, 2012, 10:27:46 amHuh? VRMs already use 12V. They are nearly 90% efficient. More efficient than at 5V, due to lower current needed at 12V.

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2012, 12:22:42 pm
content: Yeah, the losses are on the input side.So a higher input voltage results in less switching loss.12V -> 1.2V will be more efficient than 5V -> 1.2VThis is why lots of computer motherboards generate the CPU voltage using the 12V or 5V rail instead of the 3.3V rail.

author: ivan747
author_rank: Super Contributor
timestamp: July 25, 2012, 03:49:54 pm
content: Quote from: tom66 on July 24, 2012, 08:59:27 pmWell, this (if it is successful) will be used in millions of devices, enough to make semiconductor companies tweak their 24V DC-DC converters to output 20V.

author: tom66
author_rank: Super Contributor
timestamp: July 25, 2012, 09:10:04 pm
content: Quote from: ivan747 on July 25, 2012, 03:49:54 pmYes, but using already existing componentry means that it will be cheap and ready from the start, without having to wait months for development of new components and designs.

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2012, 10:41:31 pm
content: They're not going to use premade switchmode modules on motherboards for usb 3 power.For that sort of volume it would be far cheaper to design it onto the motherboard and doing so means they can design it for whatever voltages they need.Premade PCB mount dcdc modules are for low volume production, or when you need something out-the-door in a hurry.

author: tom66
author_rank: Super Contributor
timestamp: July 25, 2012, 10:44:55 pm
content: Quote from: Psi on July 25, 2012, 10:41:31 pmNo, I meant current (available)DC-DC converter ICs. Not DC-DC modules, far too expensive. Anyway, this now means a PoE enabled motherboard with USB 3.0 super-duper power needs 48V and 20V rails.I wonder if the standard will be implemented for laptops?

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2012, 10:48:22 pm
content: Quote from: tom66 on July 25, 2012, 10:44:55 pmAre you saying there are no cheap DC-DC converter ICs that can do 20V output? because that doesn't seem right.Lost of switchmode ICs are quite universal in there in/out specs. There's a wide range you can do just by changing the feedback and the inductor.

author: ivan747
author_rank: Super Contributor
timestamp: July 26, 2012, 02:20:37 pm
content: Quote from: tom66 on July 25, 2012, 10:44:55 pmMost likely it won't be implemented. Maybe they will start producing some sort of adapter that plugs into the wall and injects the 100W requested while working. The computer would see it as a hub.

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 26, 2012, 02:47:13 pm
content: Can a motherboard PCB trace handle up to 100W? I'm not sure it can. Could be wrong....

author: T4P
author_rank: Super Contributor
timestamp: July 26, 2012, 05:12:27 pm
content: Quote from: Stephen Hill on July 26, 2012, 02:47:13 pmDon't be surprised to hear high end CPU's having a TDP of 150W ...

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 26, 2012, 05:19:52 pm
content: No, a trace can not handle 100watts (handling as in dissipating). And beyond dissipation, it's somewhat pointless to relate watts to traces.If you're talking 100 watts in the context of this topic, then yes, sure it can. We're talking a mere 5 amps.Enough to seriously consider when drawing the trace, but no big deal at all.Beyond 10-15 amps things get a bit more seriously, possibly involving thicker copper, or really wide traces, but still no problem.Last week I got a Weidmuller sample kit, containing some PCB terminals for 1000V/76Amps, so that's good for 76kW.http://catalog.weidmueller.com/catalog/Start.do?localeId=en&ObjectID=1851120000

author: M. András
author_rank: Super Contributor
timestamp: July 28, 2012, 08:15:03 pm
content: Quote from: DaveXRT on July 26, 2012, 05:12:27 pmthats more than 120amps approx for a cpu btwim lazy to do the math, remember its running around 1.1-1.5 volts

author: Stephen Hill
author_rank: Regular Contributor
timestamp: July 28, 2012, 08:25:15 pm
content: Quote from: M. András on July 28, 2012, 08:15:03 pmBut a typical processor will have well over 100 Vdd, so the power is spread out over multiple pins and traces. For example, an Intel i7 has over 200 Vdd pins and can take a total of 145Amps. So that's no more than 725ma per pin/trace.

author: markus_b
author_rank: Regular Contributor
timestamp: July 28, 2012, 09:06:42 pm
content: I find that a very useful development. Now I'm waiting impatiently for interesting chips to handle the protocol and DC switching, for me to use this for my homegrown devices.On my shopping/watch list right now figures a new USB power supply with a couple of outlets. This is the ideal device to feed my lab power supply project too.

author: T4P
author_rank: Super Contributor
timestamp: July 28, 2012, 09:26:56 pm
content: Quote from: Stephen Hill on July 28, 2012, 08:25:15 pmOn a trace not much bigger than the bga pad ... But i really begin to wonder where do they dump all the 150W of heat without getting over 70C ... I worry for that. Because Sandy Bridges and Ivy Bridges max temps have gone down to 65 ...

author: tom66
author_rank: Super Contributor
timestamp: July 28, 2012, 09:37:29 pm
content: Just waiting for a USB soldering iron...

author: M. András
author_rank: Super Contributor
timestamp: July 29, 2012, 03:59:23 pm
content: Quote from: DaveXRT on July 28, 2012, 09:26:56 pmto an almost 1kg weighted copper+aluminum block with heatpipes? then to heat up the room in winter

author: T4P
author_rank: Super Contributor
timestamp: July 29, 2012, 05:09:54 pm
content: They stopped giving you aircooled heatsinks ... AMD i last recall gives you a Corsair H80-type heatsinks for the FX8150

author: M. András
author_rank: Super Contributor
timestamp: July 29, 2012, 07:25:23 pm
content: good to know thatbut if watercooling. a big 3x12cm fan radiator with high flowrate a laing d5 pump split connectors at the gpu and at the cpu to give both of them cool water. then feed them back again to 1 with the same connector after the outlets. much quiter then those corsair stuffs

author: T4P
author_rank: Super Contributor
timestamp: July 29, 2012, 07:38:32 pm
content: Quote from: M. András on July 29, 2012, 07:25:23 pmI don't care for the fan volume, those can be easily modded but corsair was the first one they went to and readily agreed to stamp their names on the water cooling systemsthose GPU's gone entirely mad, the 7970 goes 250W TDP on full load! ...And they are TBA on the 7990 ... aka the 7970 X2 ... 500W, want that? 2 of them makes for a very expensive 1kW room warmer in the winter

author: SeanB
author_rank: Super Contributor
timestamp: July 29, 2012, 07:41:12 pm
content: My watercooling at work is a cooling condenser from a display cabinet ( new spare part, the prototype was a used one) with integrated fan. Keeps the water at 24C with whatever heat it collects from 6kW of heating from the packing machine it is on. It needed a bit more cooling than it had from the 50l copper tank it has as the first improvement i added over the oem method of running tap water to waste.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 30, 2012, 03:58:09 am
content: Quote from: T4P on July 28, 2012, 09:26:56 pmJust a large heatsink and some powerful fans. My i7 will easily hold Turbo Boost with full load on all 6 cores indefinitely. I just bought a cheap but good Cooler Master heatsink, replaced the weak bundled fan with a more powerful one, and then stuck another powerful fan in the side panel.

author: T4P
author_rank: Super Contributor
timestamp: July 30, 2012, 10:28:03 am
content: Quote from: NiHaoMike on July 30, 2012, 03:58:09 amYeah, i know... Basically any cheap CM ones are a heck lot better than the stock coolerand the HSF supplied with the 980X isn't helping either ...But then again for those people who bought the 980X ... they would use the 980X "stock" cooler for something else

author: M. András
author_rank: Super Contributor
timestamp: July 30, 2012, 06:58:18 pm
content: Quote from: T4P on July 29, 2012, 07:38:32 pmi have an asus g73 with the ati card in it mobility 5970, the desktop has an 6970+1090t amd 4 core processor. playing mmorpg(not world of warcraft if anyone familiar with these) on both of them at the same time at winter my room was over 25celsius with the heating turned off

author: T4P
author_rank: Super Contributor
timestamp: July 30, 2012, 07:20:10 pm
content: I see what you mean. What kind of mmorpg have you been playing that made the 6970 went max

author: M. András
author_rank: Super Contributor
timestamp: July 31, 2012, 04:14:21 pm
content: Quote from: T4P on July 30, 2012, 07:20:10 pm"eve online" 2 client/computer, hungry little game. it has the reference cooler on it so its loud and hot. perfect room heater, the laptop consumes over 150watts when fully loaded dual fan cooled each ducting blow approx 70celsius air with a pretty good flowrate