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Volume 7 (Aug 25, 2003)
NEC Electronics presents complete USB 2.0 Solutions (1/2)
What is USB?
Have you noticed recently that it has become much easier to connect peripheral devices such as printers and digital cameras to your computer? Previously, for you to use peripheral devices, they needed to be plugged into the computer before the computer was turned on. To disconnect the peripheral device, you needed to turn off the computer before removing the device. Now, however, it's possible to plug devices in or out even while the computer is on.
Benefits such as this have been realized thanks to an interface technology called Universal Serial Bus (USB). USB allows many types of peripheral devices to be attached by means of a common connector (Photo 1). The interface can connect a maximum of 127 peripheral devices via hub devices, giving you true Plug and Play functionality. Currently, nearly 100% of all personal computers are equipped with USB, which has become the standard for computers and peripheral devices (Photo 2).
USB 1.1, the predecessor of USB 2.0, was released by the USB Implementers Forum (USB-IF) in September 1998, but as computers advanced and the number of peripherals increased, a faster data transferring interface became necessary. In April 2000, the USB-IF released USB 2.0, whose specifications provide a high-speed mode (480 Mbps) that makes larger-volume data transfers faster than ever. USB 2.0 also accommodates the USB 1.1 data transfer rates of 12 Mbps (full speed) and 1.5 Mbps (low speed), making it fully compatible with the earlier spec.
NEC Electronics' USB Achievements
Since the drafting of the first-generation USB specifications, NEC Electronics has actively participated with Intel in the USB-IF. NEC Electronics also has played an important role in bringing to fruition the transceiver function for USB 2.0, and has been a major collaborator on USB 2.0 specifications in cooperation with Intel and Microsoft. Due to its compatibility with USB 1.1 and ability to easily conduct data transfers at 480 Mbps, 40 times the speed of its predecessor, USB 2.0 is quickly growing in popularity.
In terms of functionality, USB controllers can be divided into three types: host, hub and function. NEC Electronics offers the entire line-up.
NEC Electronics supplied 4.52 million USB controllers in 2001 and 13.3 million in 2002, thereby attaining nearly 80% of the world share (Graph 1). This technology also is being released as an IP core for ASIC products, and a total of eight million have been supplied at the IC base. In addition, NEC Electronics is developing bus-powered products requiring no power source, as well as products with reduced chip size for use in energy-efficient, smaller-scale systems.
NEC Electronics Products for USB 2.0
NEC Electronics became the first company to mass-produce a host controller (the µPD720100 in March 2001) and hub controller (the µPD720110A in October 2001), and has contributed greatly to the popularization of USB 2.0 through its leadership in the USB 2.0 market. In particular, over 3.5 million units of the µPD720110A hub controller have been shipped, and it is essentially the de facto standard used by customers around the world.
In April 2003, µPD720112 and µPD720113 devices were added to the product line-up as energy-efficient versions of the µPD720110A hub controller (Photo 3). Achieving greater energy efficiency than ever before, these hub controllers internalized high-speed mode terminal resistance, paving the way for a one-chip version of the high-speed 480 Mbps interface, which was formerly an external component. In particular, the µPD720113 can handle up to seven downstream ports in products such as docking stations (functionality expansion units for notebook computers equipped with various drives, a connection terminal and expansion slots) and port replicators (functionality expansion cards for notebook computers only equipped with a connection terminal). Compared to the µPD720110A, energy consumption is decreased by approximately 56% and chip dimensions by approximately 37%. This is made possible through the use of a 0.25µm process rather than the original 0.35µm process, as well as advances in the USB buffer circuit. The size of the package also decreased due to a reduction in the number of LSI pins. Through efforts such as these, NEC Electronics now has product solutions, such as the USB 2.0 bus-powered hub, that making an external power supply unnecessary and high-speed data transfer possible.
As one of the top suppliers of USB 2.0, NEC Electronics is committed to maintaining its leadership in USB 2.0 and will continue to introduce new products and provide complete USB 2.0 solutions.
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