The iPod's central processor is a PP5002 system-on-a-chip from PortalPlayer Inc., based on a 32-bit ARM7 processor core (Fig. 2). Supplied by Sharp Microelectronics of the Americas, 1 Mbyte of memory stores system operating code. To buffer songs, 32 Mbytes of DRAM from Samsung Electronics USA is used--eight songs at about 4 Mbytes each, according to Carey. This provides 20 minutes of skip protection. The DRAM buffer lightens the disk drive's workload and prolongs battery life.
Other components found in first-generation iPods include a chip from Texas Instruments dedicated to the IEEE 1394 (FireWire) interface. The interface handles both data transfer and battery charging. A chip from Wolfson Microelectronics plc that integrates a digital-to-analog converter and a headphone driver amplifier controls audio output.
For power management, first-generation iPods include two chips from Linear Technology Corp.: the LTC1731 and LTC1726. Packaged in an MSOP-8, the LTC1731 is a complete, constant-current/constant-voltage linear charge controller for fast charging of single-cell lithium-ion (Li-ion) batteries. The LTC1726, also in an MSOP-8, combines the ability to monitor three supply voltages, at 61.5% threshold accuracy, with adjustable reset and watchdog functions. PowerFETs from International Rectifier round out the power management and control support.
When he first opened up an iPod, Carey estimated the bill of materials cost at less than $250, or roughly 50% of the retail price. By that tally, he suggested that the iPod "may be as much a hook to sell Macs as a profit generator in itself." While Apple won't say whether or not Mac sales were among its goals for the iPod, the music player has had a major halo effect on Apple.
Apple launched its third-generation iPod in April 2003, offering a 10-Gbyte model for $299, 15 Gbytes for $399, and 30 Gbytes for $499, each in an enclosure described as lighter and thinner than two CDs. Other features touted at the announcement were backlit, solid-state buttons as well as a solid-state wheel, an "on-the-go" playlist, and a customizable main menu. The 15- and 30-Gbyte models came with a dock for easier connection to either a Mac or a Windows PC. An audio line out provided easier connection to powered speakers or a home stereo.
For its third generation, Apple down-shifted its continuous play spec from 10 hours to eight. Perhaps by factoring in the effect of more compact file formats, it upped the song capacity of the 30-Gbyte models from 6000, which would have been expected in a linear progression, to 7500.
Comparing the third-generation iPod to the first, Portelligent's Carey found the enclosure, hard-disk drive, solid-state touch-scroll wheel, SoC, flash, DRAM buffer, FireWire interface, and audio chip to be about the same in each (Fig. 3). The third-generation units are 1.57 cm thick. This is due in part from Apple's swapping of the lithium-polymer battery in its first-generation iPods for a smaller, less-expensive Li-ion cell. In addition, Apple set both the new battery and the hard drive into a cutout on the main board, reducing the profile of each. Plus, third-generation players include a USB interface chip from Cypress Semiconductor Inc.
The third-generation iPod contains two power-management chips from Royal Philips Electronics, a TEA1211 and a PCF50605. The TEA1211 is a dc-dc converter that can switch automatically between step-down and step-up operation in response to changing input voltage. The PCF50605, a single-chip power-management unit (PMU), can adjust power-supply voltages to the lowest thresholds needed for functions in a particular power domain.
In September 2003, Apple unveiled a 20-Gbyte model priced at $399--the same price as the 15-Gbyte model introduced just five months earlier--and a 40-Gbyte model priced at $499 that holds up to 10,000 songs.
Soon afterward, Apple made iPod software available to Mac and Windows users, adding support for Belkin voice recording and photo storage accessories for dockable iPods. Thus, users could record hundreds of hours of audio and store thousands of digital photos on their iPod.
By January 2004, Apple had shipped some 2 million iPods. That month, it introduced the iPod mini. With room for 1000 songs, plus extras, the 3.6-oz., 1.27-cm mini presented a cleaner look than earlier iPods. The buttons below the display screen were eliminated, and their functions were transferred to the outer ring of the scroll wheel.
Tearing down the mini, Portelligent's Carey found a new PortalPlayer CPU chip (PP5020D-TF) that, for the first time, integrated USB and FireWire controller functions (Fig. 4). In lieu of Toshiba's 1.8-in. drive, the mini employs a 1-in., 4-Gbyte Microdrive from Hitachi Global Storage Technologies. A Linear Technology LT4055 USB power controller/Li-ion linear charger can detect the presence of a wall adapter and use it as an alternative power source to charge the battery while simultaneously providing power to the load. Other power-management devices include a Texas Instruments TPS62046 step-down dc-dc converter and an LM3485 PFET switching regulator controller from National Semiconductor Corp.
One of the latest additions is iPod Photo. It comes in 40- and 60-Gbyte models that hold 10,000 or 15,000 songs, respectively, as well as up to 25,000 digital photos. The units feature up to 15 hours of music playback or up to five hours of slideshows. Both Mac and Windows users can exploit iPod Photo via Auto-Sync.
Please refresh the page if you have trouble reading this text.
Search Electronic Design
Email Newsletter
Sponsored By:
The Find Power Products monthly newsletter brings you the most important new developments within the world of power design. The newsletter includes exerpts from industry leader Sam Davis's exclusive blog, as well as overviews of the latest new products.
Enter Email to Subscribe
Web Seminar
Sponsored By:
Title: Exploring How Good GUIs Drive Adoption in the Digital Power Management Space
Reprints
