New USB specification promises 100W of power

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.

The third generation of the Universal Serial Bus standard introduced high speeds of up to 5Gb/s, but also added increased bus power of up to 900mA at 5V for more complex devices. This latest update goes a step further, however: allowing variable voltages and up to 100W to be negotiated over USB, the new standard will greatly increase the flexibility of USB devices.

Announced today by the USB 3.0 Promoter Group, the USB Power Delivery specification is designed to co-exist with the current USB Battery Charging 1.2 specification and includes backwards compatibility with USB 2.0 as well as support for USB 3.0.

"Building on the rapidly increasing industry momentum for using USB bus power to charge a broad range of mobile devices, the new USB Power Delivery specification extends USB's cable power delivery capabilities beyond simple battery charging," said Promoter Group chair Brad Saunders at the announcement. "For example, charging the battery of a notebook PC, or simply powering that notebook PC while actively using the USB data connection, would be possible. Conceivably, a notebook PC could rely solely on a USB connection for its source of power."

That latter mode is enabled thanks to a clever system whereby a USB port can act as either the source or the recipient of power depending on requirement, allowing a USB port on a laptop to double as the charging port and finally doing away with the various proprietary power connectors used by different manufacturers.

A massive increase in power output - from a maximum of 4.5W to 100W - isn't going to be straightforward, however. The USB 3.0 Promoter Group claims that the USB Power Delivery specification will be ready for industry review towards the end of the year, with the final specification expected in early 2012. No time scale has yet been offered for a commercial implementation, however.