Phyton, Inc.

<p>Click here for Figure 7</p>

Planning for successful implementationWhen selecting a gateway, it's essential to not only plan for the correct number of voice channels required by users, but also to select a gateway that can scale easily to support future demands, and that can support multiple VoIP protocols and open industry standards. This scenario retains the old PBX and internal voice network, so you needn't worry about ensuring that an internal IP network is able to carry VoIP traffic. However, any IP link that carries time-sensitive traffic, such as voice, must offer sufficient performance and capacity to meet quality-of-service demands.

Finally, the file-system sits on top of this memory stack, logicallymapping files to sectors and providing director services. Two types offile-systems exist: traditional FAT file systems that have only amaster allocation table (Windows FAT32, for example) and transactionalfile systems that keep a log of each transaction to prevent anoperation from being corrupted if power is lost.

For designers to transition from voice-centric NOR flash memory tohigher-performing NAND flash memory, integration software support isimperative. Handsets account for roughly half the NOR flash market andsuch embedded applications as hand-held industrial scanners, varioussecurity devices, remote sensors, GPS systems and even network serversaccount for another quarter or more of the market.

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Lower-volume applications When millions of consumer products are produced from a single design,custom software is a relatively inexpensive. But software developmentis a prohibitive cost for most embedded products, where productsgenerally number in the hundreds of thousands of units or less. Suchproducts employ many operating systems and widely varied hardware,therefore software to support a NAND flash design must be versatile aswell as inexpensive.

Accordingly, now available is prepackaged flash software support forthe OneNAND fusion flash architecture to work smoothly in embeddedapplications, the result of a cooperative venture between the softwaremanufacturer Datalight and Samsung. This will hasten theNOR-replacement time line for certain applications, particularly thosethat require 128 Mb to 1 Gb of memory and a separate file system, withfrequent data writes.

NOR flash memory has become less practical to use than NAND flashmemory in new generations of mobile products in which multimediafunctions are the driver, though NOR will continue to be use invoice-centric handsets. However, a sharp rise in demand for NAND callsfor greater care in planning by consumer-electronics OEMs,embedded-systems designers and industrial-device designers asapplications grow more complex, use faster processors and have agreater need for memory.

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Don Barnetson is associate director of flash memory marketing atSamsung Semiconductor, Inc.

Sometimes it seems as if the 802.11 Wi-Fi marketplace behaves like a vacuum, sucking in every enhancement, with no end in sight. As has often been the case in the past in our industry, technology vendors have taken to surpassing the performance levels specified in the pertinent standards as a way of continuing the growth of the marketplace.

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Indeed, there are legitimate ways of enhancing 802.11 while remaining in conformance with the standard. Here are some tips on what to look for when you're putting together a wireless local-area network (WLAN) and evaluating the enhanced” features of various Wi-Fi products.

First, make sure it's Wi-Fi-certified. This may sound so fundamental that it's obvious, but it's worth repeating over and over, because certification usually ensures interoperability, which is essential in the real world.

WHAT IT DOES: Supplies three independent music streams simultaneously and offers music and image organization.

HOW IT'S DIFFERENT: The SMS3-250, the latest in Russound's line of Smart Media Servers, comes with a 250-Gbyte hard drive that can store six months' worth of nonstop music. The SMS3-250 makes three streams of music available at the same time from anywhere in a home to any listener, suiting it for multiroom systems. Three listeners can select and play music from CDs, MP3 or Internet radio at the same time in any area connected to the home's audio-video system. The system can be controlled from a PC, the SMS3 remote control or Russound's UNO keypad.

The server's Personal Media Assistant remembers music choices and learns listening preferences, tailoring selections to users' tastes. The server comes with an easy-to-navigate TV screen interface that displays artist information, track and selections, and album cover art retrieved from the Internet using the Gracenote and Muze online databases. When the SMS3-250 is integrated with Russound's RNET-based systems, the information can be delivered to the company's UNO keypads. The data also may be shown on a TV or PC. Music can be categorized by artist, genre, theme or playlist.

Enhanced slide show capabilities let users create slide shows to be broadcast to any home-networked display. Users can set the slide show to music.

Available via the media server setup screen, these features give homeowners more options for enjoying digital audio and pictures,” said Andy Lewis, RNET product manager at Russound.

While the relative simplicity and familiarity of the flyback converter has its advantages, the SEPIC converter can provide higher efficiency and lower component stress. Table 3 compares the two approaches. The SEPIC is more efficient because semiconductors with lower voltage ratings can be used, due to lower circuit-voltage stresses. Component count is similar for the two designs, but the flyback has the disadvantage of requiring snubbers. While the component areas are equal, the flyback’s transformer could be made smaller because its inductance requirement is one-half that of the SEPIC’s. Continuous input current not only reduces the SEPIC’s input-capacitor ripple-current rating, but it also improves a system’s electromagnetic emissions. If there are other loads on the 12-volt input, the flyback’s discontinuous input current is more likely to generate an unacceptable ripple on the input, which may require additional filtering. One downside of the SEPIC is that it has an additional passive component, an AC-coupling capacitor, which complicates the control characteristics. However, when implemented correctly, the SEPIC converter provides an excellent, highly-efficient solution.

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