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Behold the power of USB

Posted: 01 Nov 2007 ?? ?Print Version ?Bookmark and Share

Keywords:USB advantages? universal connector? USB power?

An obvious advantage of having USB as the universal connector in mobile apps is its cost-effectiveness. In the years to come, more CE products will indeed be powered through USB.

Before the USB standard was widely adopted by the "wired" communications world, the Serial RS-232 port and the parallel port were the de rigueur interface standards. Ten years ago, no one could have imagined that the USB standard would enjoy the success it is seeing now.

USB ports are found in some one billion devices throughout the world today, and this trend is likely to continue growing in the future. Some reasons for the USB standard's popularity include its "plug and play" capabilities; ease of connection with other peripherals; and higher data transfer rate compared with many other common communications standards. Another key reason is its ability to supply bus power supply. Many are unaware that the USB can do more than just transfer data and supply power from the PCit can also act as a power supply unit.

Years ago, the AC power socket or battery were the power sources most commonly used for consumer electronic products such as lights, fans, shavers, chargers and media players. Today, the USB port is becoming another important power source. Supplying power from the USB port can sometimes be easier than using the AC power socket.

More and more consumer products are using the USB bus power supply. The ready availability of USB power supply is changing consumers' usage of traditional AC power, resulting in greater convenience and the need for fewer components in products. It delivers low-cost, clean, safe and soft power.

USB as power supply looks set to become even more widespread with the China government's recent announcement that cellphones designed after June 14, 2007 must use the universal charger interface that is based on USB. An obvious advantage of having USB as the universal connector in mobile applicationsbe it for power or data transferis its cost-effectiveness. A single battery charger/connector can be used by handset manufacturers, resulting in fewer resources needed to get a phone to production and more cost savings. Once the USB port becomes the unified interface for all cellphones and chargers, it is possible that there may be at least several billion USB devices supplying power to consumer electronic products globally.

USB bus power supply has its limitations and constraints, though. For example, USB hard disks, DVD/CD players, printers and speakers need extra AC power adaptors because of the 500mA current limitation of the USB bus power. In addition, it may not be possible for some USB devices to be correctly attached to PC USB host ports, because of the Vbus voltage drop. (The supply voltage of USB ports is out of the USB specification of 5V 5 percent).

We are very fortunate that USB standards are continuously being improved and perfected, and it is only a matter of time before the next-generation USB 3.0 standard will be adopted. It is predicted to be capable of supplying more power (with a minimum of 10-50W power for most portable CE products), a wider range of voltages (3-40V, if possible) and more current (likely to be in the range of 3-5A). Moreover, its Vbus power limitations and constraints will not be as limited as that of USB 2.0.

We can truly foresee that in the years to come, more and more consumer electronic products will indeed be powered by USB, making the promise of USB power come to life.

- Antonio Alvarez-Tinoco,Senior Director and General Manager
Product Line USB/WUSB
Asia Product Innovation Center
NXP Semiconductors

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