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Volume 55 (Apr 12, 2006)
NEC Electronics' Audio Processor: Making 50 Hours of Continuous Music Playback on Mobile Phones a Reality! (1/2)
< Part 1 >
Realizing extended playback with the µPD99910 audio processor
This article introduces the features of NEC Electronics' µPD99910 audio processor for mobile phones, a product that enables 50 continuous hours of music playback.
The demand for audio processors capable of extended playback
Music functions on mobile phones have become increasingly advanced in recent years, and the content on web sites dedicated to music has been enhanced. Downloads for songs that can be downloaded in their entirety have already exceeded 30 million in Japan*1, and music distribution services for mobile phones are expected to witness even further enhancement in the future. Meanwhile, mobile audio players capable of recording music onto memory or hard disks are fast gaining popularity. As a result, consumers are now seeking mobile phones with functions identical to those of mobile audio players, including the ability to import and download music data from compact discs and the Internet.
Due to the expansion of mobile phone functions such as these, it is now commonplace for mobile phones to be equipped with not only baseband LSI devices for carrying out the processing of basic functions such as transmissions and calling, but also an LSI device capable of processing music playback and camera functions, images and Web browsing. This type of processor is referred to as an application processor. The application processor's CPU and DSP are used when music playback is performed, but since this requires a measurable amount of power, extended playback is impossible. It is currently said that five to six hours of continuous playback is possible; however, since mobile phones use functions other than music playback, for example, calling, text messaging and browsing the Internet, the actual amount of playback time is only about half that. Power consumption must therefore be reduced to achieve extended playback comparable to that of mobile audio players without concern for battery life.
NEC Electronics' audio processor and its features
To meet these needs, NEC Electronics developed the µPD99910 audio processor as a dedicated LSI device. The µPD99910 is an LSI device specifically created for the music playback functions of application processors (Figure 1).
The µPD99910 incorporates both a low-power-consuming CPU for music playback processing and a DSP within an LSI device and consumes only 10 mW of power even during music playback. Music can therefore be played without operating the application processor's CPU or DSP, both of which consume a great deal of power, thereby realizing 50 hours of continuous music playback, more than twice what is currently possible. (This figure is based on data from an in-house comparison in which calculations were made using data based on the Secure Digital Music Initiative. Data was compressed using the AAC method with a data-transfer rate of 128 Kbps and audio output sampling frequency of 44.1 kHz.)
In addition, the chip size of the µPD99910 was decreased to reduce the size of the package area as much as possible. The package uses a 6 × 6 mm 97-pin TFBGA and is compatible with compact, low-profile products (Photo 1).
The µPD99910 also incorporates a function for interfacing with a small-scale memory card referred to as an "SD card," which has a copyright protection function for downloading music from the Internet. And since µPD99910 supports the SD card's Content Protection for Recordable Media (CPRM) technology, music data can be downloaded and played without worry of copyright infringement.
Up until now, NEC Electronics has offered a wide variety of audio-playback-use LSI devices matching the mobile phone needs of the times, from monaural and stereo surround to multifunction. In the future, we will continue to aim to be among the first to develop technological innovations that meet the music playback needs of the latest mobile phones to help reduce the development burden faced by the growing ranks of mobile phone manufacturers.
In Part 2, we will discuss the appeal of the µPD99910 as well as look back at the innovative ideas used and the hardships faced during its development.
Note(*)
- As of December 28, 2005
228KB)