USB charges up to 100 watts
One cable to rule them all while avoiding e-waste
The USB Promoter Group has a new ambition: using the ubiquitous connectivity standard to power your laptop while
saving the planet eliminating the need for proprietary power bricks along the way.
The general idea, as outlined in the newly-completed USB Power Delivery Specification, is to deliver up to 100 watts over USB.
That level of joltage, the Group says, will make USB “... capable of delivering higher power to charge notebook PCs and power external hard-disk drives, devices which previously did not receive adequate power from traditional 5V bus power.”
The Group is also talking up new types of device that pipe the 100w into your laptop, or other gadgets.
Brad Saunders, USB 3.0 Promoter Group Chairman, describes them thusly:
“We envision a significant move toward universal charging based on this specification, most notably for charging notebook PCs using standardized USB power bricks or when connected to USB hubs and desktop displays that integrate USB Power Delivery capabilities.”
We think that means the Group imagines USB Power will be built into monitors, which will suck images out of laptops while charging them at the same time. The Group is also talking up the possibility of using one USB-charger, and associated hubs, to charge multiple devices. That arrangement will, it is hoped, result in fewer proprietary power bricks being shipped and less redundancy and waste for those that are summoned into existence.
The 300-plus page spec (15MB PDF) for the standard offers colossal quantities of detail about its workings, including that it will have five "profiles", each of which delivers different amounts of power. USB ports on devices will be rated to work with different profiles.
The five profiles are:
- Profile 1 capable of supplying 5V @ 2.0A
- Profile 2 ports are capable of supplying 5V@ 2.0A, 12V @ 1.5A.
- Profile 3 ports are capable of supplying 5V @ 2.0A, 12V @ 3A.
- Profile 4 ports are capable of supplying 5V @ 2.0A, 12V and 20V at 3A respectively.
- Profile 5 ports are capable of supplying 5V @ 2.0A, 12V and 20V at 5A respectively.
The one fly in this one-cable-to-rule-them-all vision is a requirement for “USB Power Delivery certified cables”, which devices will detect as capable of handling the firmer flow of electrickery the new standard enables.
The spec says the new cables "... have been significantly improved to increase their current carrying capability (5A for the standard connector and 3A for the micro connector), and to allow them to be electrically identifiable while remaining mechanically compatible with the existing connector set."
Old USB cables will still work, and won't melt, but won't carry the extra current. ®
Re: How exactly are they doing this?
RTFA. The article provides the information, but you do have to actually read it..
Sounds great apart from this: http://xkcd.com/927/
Re: Why not?
'or take the frequency to 1000Hz'
Surely it's DC through a USB.
Re: Why not?
> take the frequency to 1000Hz so the voltage can go higher without killing people.
What has frequency got to do with lethality? 230v can kill you as easily at 1kHz as it can at 0Hz, 50v is unlikely to kill you at either.
Re: Great idea!
What? I can't run my kettle off my laptop USB port!
What good is that?