Electronic Design
Inside The Apple iPad

Inside The Apple iPad



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The Apple iPad has arrived and has satiated demand for at least half a million users the first day of its release. Inside, the $499 iPad is a combination of standard components and custom chips designed to give the iPad fast response as well as long battery life. It is only half an inch thick and weighs in at 1.5 pounds.

iPad Teardowns

We are still waiting to get an iPad in the lab but in the meantime there are a couple sites that have already open the box and cracked the lid on their iPads. The Chipworks teardown is the most extensive. This teardown digs inside the chips as well as the interior of the iPad. Chipworks actually collaborated with the iFixIt teardown. Both provide detailed chip and hardware analysis that provided us with more insight into the iPad. Chipworks actually took apart the Apple A4 Package-on-Package (PoP) chip to expose the pair of memory chips stacked on top of the ARM processor

The other advantage of these teardowns is it highlights the mechanical construction of the system. It also provides a repair path for those who are so inclined although much of the system is contained on a couple boards that would not be repairable by anyone. Still, the teardowns provide insight into how Apple has been able to deliver the performance and battery life necessary for a succesful tablet platform.

iPad Hardware

The heart of the system is the Apple A4. This package-on-package (PoP) chip uses technology common on smart phones where real estate is at a premium. The base looks like ARM's Cortex-A8 processor. It has a pair of 1 Gbit memory dies above it for a total of 256 Mybtes of on-chip RAM. The PoP approach allows the memory to be tested before assembly. It also allows the memory to come from different sources. Close proximity to the processor allows better electrical optimization because of shorter routing, less crosstalk and better noise immunity compared to off chip memory. The A4 is connected to a pair of 8 Gbyte MLC NAND flash chips.

The iPad multitouch display is based on a 9.7-in LCD display with a 1024 by 768 pixel resolution. Novatek provides the LCD drivers for the LED-backlit display. The system employs Broadcom's BCM5973 and BCM5974 I/O controller plus a Texas Instruments CD3240A1 to handle the touch screen interface. This three chip approach is less expensive although it uses more board real estate than the single chip solution used with Apple's iPhone. Movement and orientation is detected using an STmicroeletronics accelerometer. A light sensor checks the ambient light conditions.

The pair of 3.75 V lithium polymer batteries are designed for 10 hours of use. The 24.8 watt-hour batteries are wired in parallel. The 10 W USB power supply is provided by Foxlink Technology.

The 802.11n WiFi/Bluetooth card is integrated into the dock connector cable. It utilizes a Broadcom BCM4329XKUBG chip. 3G support will be integrated into a future iPad model and was not included in the first group of WiFi-only iPads.

The iPad has a pair of speakers, but they are mounted next to each other providing only mono sound. A pair of channels direct sound toward the side of the iPad. The audio-out jack delivers stereo sound.

iPad Software

The iPad is delivered with the iPad OS 3.1. It is essentially an updated version of the iPhone operating system designed to handle the larger screen. Like the iPhone, the primary application delivery system is Apple's App Store.

The iPad comes with a core set of applications designed for the web and multimedia content starting with Apple's Safari web browser. It currently does not support flash but there is plenty of online video content that uses other codecs such as H.264 that is included in Safari.

The mail program works with the on-screen keyboard. The display is large enough for a full QWERTY keyboard, and the multitouch support is significantly better than most systems but it is still short of a physical keyboard.

The photo gallery application is a much larger version of the iPhone application. Obviously it uses the multitouch interface making movement and zooming just a finger flick. Of course, there is support for local and Internet video viewing. Both YouTube and iTunes are standard applications.

The iBook application integrates with the iBookstore, essentially an offshoot of iTunes and the App Store. There are some free books but this is obviously a venue to take on Amazon's Kindle. The display is an LCD so it is possible to put better animations within a book compared to an ePaper display, but the power requirements are higher for the iPad's LCD display.

There are a host of other applications included with the iPad such as a Maps application, notepad, calendar, contacts, and search. The iWork suite handles documents, presentations, and spreadsheet with charts and graphs.

iPad Success

Any product that sells half a million units in a day is a success and Apple is on target for selling a lot more over the next few years. It is already drawing out the competition. Tablets are not new but the success in the past tended to be in dedicated applications where developers could tune the applications to the hardware. Apple has done this across the board with its suite of applications. This was lacking in most prior attempts at pushing tablets into general use including Microsoft's half hearted attempts and even Apple's own missteps with the Apple Newton.

One thing to note is the major differences between the iPad and prior tablet incarnations. One major item that is not highlighted is handwriting and character recognition. Likewise, a stylus is not part of the iPads options while multitouch is.

The other piece to the puzzle is consistency between the base applications and the flood of apps from the App Store. Many of the applications will have iPhone heritage but the larger screen opens the possibility for business and enterprise applications. The big mistake that occurred with Windows tablets was this class of applications were typically reworks of WIMP (window, icon, menu, mouse) applications. The menus tended to highlight the precision of the stylus required on most platforms. Many may view the iPad as a new slate and develop new applications or significantly rework existing applications before delivering them on the iPad.

New competition will be coming from all areas including lower cost alternatives as well as Windows-based solutions. Likewise, the iPaper eBooks have already garnered a following but the level of inconsistency between platforms, the use of DRM and proprietary online store distribution systems continues to plague the competition.

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