With sexy styling, an ultra-thin design, and an easy-to-use interface, Apple's the iPod has energized the personal audio player market, making it the latest trendy product being purchased by people of all ages. Not surprisingly, Apple and its partners have introduced a wide array of peripherals that enable owners to personalize their iPods and extend their use. Accessibility has expanded into to the car, as well as to the home and office, with RF transmitters, docking stations, and a multitude of external speaker options.
In addition to giving users many ways to use and personalize their iPods, Apple's strategy includes rapidly bringing new products to market to address different price points, size niches, and with the recent latest iPod Video introduction, new capabilities to keep the competition in the distance.
For the semiconductor companies enabling the iPod family's functionality, they share in the huge sales and marketshare enjoyed by Apple. Apple has remained loyal to the same audio suppliers as with the first-generation iPod, but with different versions of their products. The only exception is the iPod Video, in which Apples has introduced a new supplier to support new functionality.
For the audio processing, PortalPlayer provides several variants of its PP50xx family, depending on the specific iPod model. All PortalPlayer's devices also support peripherals and control, such as memory, USB, and hard-disk interfaces (see the figure). For the audio codec, Wolfson Microelectronics provides multiple versions.
The new supplier enabled by the iPod Video is Broadcom. Its BCM2722 facilitates the video decoding and processing.
A generic iPod employs the functionality and architecture shown.
The audio capability of these players requires audio processing and an audio codec. For audio processing, PortalPlayer’s PP5002 is the digital audio system IC used in the first, second and third generation iPod players. This device uses two 32-bit ARM core processors providing 180MIPS for the encoding and decoding of the digital audio.
For the first generation of the iPod Mini, Apple selected PortalPlayer's PP5020 (see the table). With a die size of 6.1 by 6.1 mm in a 240-ball BGA package, this device uses the same ARM-based core processors, clocked at 80 MHz, for 160 MIPS. As a result, this less-powerful version of their audio processors consumes less power, thereby extending the battery life in the smaller iPod Mini.
The second generation iPod Mini uses the PP5022, with a 4.6- by 4.6-mm die size, in a 261-ball BGA. Designed in a 0.13-micron technology, it delivers up to 200 MIPS of processing power and reduces power consumption by 300% compared to the PP5020, extending the playing time between battery charges.
For the fourth-generation iPod and iPod Photo, Apple returned to using PortalPlayer's PP5020. This is likely due to the fact that the less powerful system-on-chip (SoC) met all the processing requirements and enabled Apple to speed up design time by using the same device for multiple products. In addition, Apple likely negotiated a better price for the IC due to the higher volume. Both the Nano and Video use the PP5021C, which is believed to be a lower power consumption version of the PP5020, with some minor changes.
From the audio processor, the digital audio signal is sent to the Wolfson Microelectronics audio codec, where a digital-to-analog conversion takes place before this analog output is sent to the headphones or external speakers. The first- and second-generation iPods used Wolfson's WM8721 audio digital-to-analog converter (DAC). This part incorporates two 24-bit DACs with an integrated headphone driver for good compatibility to the PortalPlayer audio processor.
For the third-generation iPod and iPod Mini, Apple selected the WM8731. This codec incorporates two DACs and two ADCs, along with an integrated headphone driver, programmable sample rates, ADC high-pass filer, and audio data interfaces. The ADCs enable the iPods to support microphones or other analog inputs.
For the 4th generation, Photo, and Nano models, Apple employed Wolfson's WM8975, which is similar to the WM8971. This stereo audio codec adds digital signal processing for graphic equalization, while operating at lower supply voltages for reduced power consumption. The iPod Video uses the WM8758, which offers a die size of 3.0 by 2.8 mm.
In the iPod Video, Broadcom joins Apple's coveted list of suppliers with the BCM2722. This multimedia processor provides both video processing and codec functions. The codec function is provided in software and supports MPEG and JPEG standards. Designed at the 0.13-micron process node, and with a 4.6- by 4.6-mm die size, this 281-pin multimedia processor uses Broadcom's VideoCore II engine, in contrast to PortalPlayer's use of dual ARM-core design. If Broadcom decides to add ARM cores to its next-generation product, it could also manage the audio processing and potentially displace PortalPlayer from future iPods. The BCM2722 also supports other functions not utilized in the video iPod, such as a digital camera controller and MemoryStick interface. Perhaps these will appear in future iPods.
As with the PortalPlayer SoC, Broadcom's processor integrates an LCD controller. However, Apple is using a separate LCD driver/controller from Toshiba in the iPod Video. For their other products with monochrome or color LCDs, Apple uses Renesas ICs. The Renesas HD66753 LCD controller/driver is used in all Apple products with a grayscale display. The iPod Photo uses Renesas's HD66789R, which supports a 176- by 240-pixel display and 260,000 colors. The iPod Video uses a product from Toshiba for the 16-bit color, 2.5-in. LCD color panel.
About the author
Gregory A. Quirk is a technology analyst for Semiconductor Insights. He can be reached at gregoryq@semiconductor.com.
This article is excerpted from Semiconductor Insights' MP3 Player Design Win (MDW) subscription service.
