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USB 3.0 to get high-power charging for notebooks, tablets

updated 01:40 pm EDT, Tue August 9, 2011

USB 3.0 Power Delivery Spec to allow up to 100W

The USB 3.0 Promoter Group just revealed it is working on a new power delivery spec for USB cable bus power that will deliver much more power for charging or powering electronics devices. The standard will exist alongside the USB Battery Charging 1.2 specification and deliver up to as much as 100W of power. It will also continue to work with USB 2.0 and original USB 3.0 standards as well as current cables and connectors.

The source of power delivery will be switchable without the need to change the direction of the cable. Notebooks could be powered and use the USB connection to transfer files using a single USB cable, or rely solely on the USB for power.

The USB Power Delivery spec is planned to undergo industry review this fall. More information will be made available at the Intel Developer Forum in mid-September. A final spec will be sent to the USB Implementers Forum early in 2012 for publication, by which point companies can start working on products.

Power has become an increasing problem with USB as the normal 5W limit has become a limit for some. Tablets like the iPad often use closer to 10W of power and have to either use specific ports to charge or resort to AC power.

by MacNN Staff



  1. prl99

    Joined: Dec 1969



    That's a low of current flowing through a small connector. That's half of what Apple says a 21.5" iMac uses under continuous power. Why would someone want that much power going through an interface cable? Think about the heat being generated and the potential for shorting the connector. There's a big difference between the 5W in USB-1/2 and 100W. Talk about laptops catching fire, here's a place they could.

  1. Inkling

    Joined: Dec 1969


    Current flow

    A simple electrical calculation does raise serious issues. At 5 volts, 100 watts requires 20 amps. To pass that sort of current safely, you need wire the size of most house wiring. A pair of 12-gauge wires, suitably insulated, is about the size of a standard USB connector. It'd be stiff, heavy and not very portable. And it would exhaust most laptop batteries in a matter of minutes. Why would anyone want to bother with that?

  1. The Vicar

    Joined: Dec 1969



    The USB spec has always been full of overpromise and underdelivery. (Look at the way USB 2 speeds were still lower than FireWire in practice, and dropped dramatically if you mixed USB 1 devices into the chain.) By the time this actually gets into production, it will turn out to deliver a maximum of 20W, and only work if you use the cable for nothing but power.

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