News - New USB standard will deliver up to 100W of power

[Workaholic]

Sounds good and great for reducing the mess of electrical cables/transformers near the wall.

Main problems that I can think of are:
* Laptop battery life when devices connected (although I'm sure a power saving option would be introduced)
* How many/big a PSU would you need?

[Funkstar]

2) people will think their old cables will be suitable to carry such large currents.

Well they can try, but the controller will know it isn't a new style cable and will drop down to USB2 or USB3 power levels at the maximum. This is in the article.

[Funkstar]

* Laptop battery life when devices connected (although I'm sure a power saving option would be introduced)
* How many/big a PSU would you need?

All this depends entirely on what you are powering. Your laptop battery will only be effected if you have higher than normal-power devices connected, just like your battery life goes down when you connect an external USB powered drive today. Pretty much most things you are likely to power that will suck down a lot of juice are going to want to be sat on a desk anyway (Monitor, printer, very large disk, etc.).

A great deal of this proposal isn't to make everything chargeable/powered by a PC/laptop, that is just a happy by product and adds flexibility. Clearly this group want a universal charger/power adapter for devices up to 100W, moving away from a simple round two pole plug adds far more scope to do something really clever. After all, the connector is already fairly universal in many situations, why not make it truly universal.

[peterb]

The technical details are sketchy (non existent) in the press release, but there are a number of ways in which the power can be regulated.

The new cable could have multiple power conductors, sharing the load current between them. The power could be delivered at a higher voltage over certified cables (with additional conductors solely for that purpose) with a DC/DC converter at the peripheral end. Remote voltage sensing could be used to detect voltage drop to detect inadequate cables.

There is certainly the implication that there is some firm if power negotiation that will take place.

Power delivery over signal cables is not new, power over ethernet is one example, but this does seem to introduce the promise of a lot more versatility to the USB interface.

[Gkpm]

Well they can try, but the controller will know it isn't a new style cable and will drop down to USB2 or USB3 power levels at the maximum. This is in the article.

Yes, but that doesn't stop confusing many users who don't fully appreciate that USB cables can be different, if the connectors are the same.

I work in AV and already see a lot of queries from people buying underspecced HDMI cables and running into troubles.

[d0dge]

I can see a problem with this. Most Laptop AC adapter are around 65w. Adding this to the spec would mean a 165w adapter for your laptop which would be a huge brick. I can only see this being practical for desktops.

[cameronlite]

I quite like how the device can "request" how much power it wants.

"Hi Computer, I've just left my 1 year warranty... Think you could hook me up with some of that 100W goodness?"

[dangel]

I quite like how the device can "request" how much power it wants.

"Hi Computer, I've just left my 1 year warranty... Think you could hook me up with some of that 100W goodness?"

Yes but we can finally have a USB coffee warmer that works!!!

[peterb]

I quite like how the device can "request" how much power it wants.

"Hi Computer, I've just left my 1 year warranty... Think you could hook me up with some of that 100W goodness?"

Request is probably the wrong word. Power required is a design parameter, so the negotiation will be to tell the controller how much power it requires and maybe the voltage it needs.. The current taken is proportional to the applied voltage.

[Hamy144]

What devices actually need 100w of power?

[crossy]

What devices actually need 100w of power?

Jeremy Clarkson's coffee warmer?

[TooNice]

Here's a thought: a laptop that runs on USB

[DDY]

Here's a thought: a laptop that runs on USB

We could do that with the current USB standard, we would need 780 Y cables in 8 AWG for a 100W laptop.

[Jay]

20A would melt that cable and give you quite a kick

[TheAnimus]

All certified USB devices must request the power in units of some amount, about 5ma iirc, most do not, they simply take as much as they want!

If this is voltage, from a current source, which is regulated by the host chip this will also put a stop to that bad pratice whilst making many opportunities, exciting!