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By Brian Dipert, Senior Technical Editor -- 9/30/2008 EDN
![]() I admit it; I am?such?a wimp. I get my hands on an expensive and hard-to-disassemble (or more accurately,?reassemble) widget, and all of my best-laid?Prying Eyes?plans go out the window. Fortunately (for me), as was the case with my past analyses of the?Microsoft Xbox 360 Elite?and?first-generation Apple iPhone, for?Apple's recently introduced second-generation iPod Touch?I was able once again to find someone who'd?already?done the dissection and was willing to partner with me, providing high-resolution images (click any of the images below to see iFixit's full-size pictures) and answering any follow-on questions I might have.
My collaborator this time around is?iFixit, a site I've?mentioned plenty of times before. And fortunately (for you), since I still have an intact unit in hand by virtue of my leverage of iFixit's pre-existing work, I'll be able to supplement this writeup with plenty of hands-on perspectives on the device. Keep an eye peeled on the?Brian's Brain?blog for usage tidbits to come.
In this writeup, for reasons of brevity, I'll bypass many of the step-by-step intermediary teardown photos and corresponding descriptions. To round out your education, therefore, I encourage you to supplement your reading of this Prying Eyes piece by also perusing the?First Look on iFixit's site. RapidRepair also did a dissection; the images and verbiage in?that company's Repair Guide?may also be of interest.
Crack open the diminutive Apple product packaging and you'll find the following goodies inside (clockwise from the top):
- A plastic inner package
- A dock adapter and a rolled-up cleaning cloth
- A USB cable and headphones
- Product documentation
- The iPod Touch itself, and
- A protective clear plastic covering for the unit's touchscreen LCD, pre-printed with a simulation of what the display looks like when the iPod touch is turned on.
Pry away the front panel, and the internal components start to become visible.
The connector in the upper left corner mates with the unit's ambient light sensor, used to control the LCD backlight. And in the upper right corner is a portion of the 2.4 GHz antenna. Between them is a mysterious grey rectangle; later in this writeup, I'll tell you what's under the lid.
With the internal assembly removed from the rear chassis, its back-side becomes visible.
Note the enormous flex interconnect that mates the majority of the system circuitry, at the bottom of the unit, to another mysterious grey rectangle at the upper right corner of the photo. Its contents? Again, hold that thought for a few paragraphs. Note, too, the narrow flex cable which routes up to the side-located volume controls, new to this second-generation design.
The touchscreen LCD attaches to a mating metal backing plate (which provides additional rigidity) using only a few strips of tape.
On the other side of the metal plate is the system's lithium-ion polymer battery. Here's a closer view of the front-side assembly with the touchscreen LCD (3.5-in. diagonal, with 480×320 pixel resolution and 163-pixel/in.2?pitch) removed.
And here's what the reverse side of the battery looks like. The Apple-coded part number doesn't enable me to decipher the charge storage capacity.
Now it's time for some extreme close-up views. This is the lower end of the front-side assembly.
The dock connector, with?encryption support in this product generation, dominates the landscape. Above it in the left corner is the connector for the cable that tethers the PCB to the LCD touchscreen. In the middle of the shot is the actuator for the iPod touch's primary control button.Portelligent's?David Carey, with whom I partnered for the?first-generation iPhone Prying Eyes project, tells me that the STMicroelectronics-supplied accelerometer is the largest IC on this particular piece of PCB real estate. In playing around with various Apple- and third party-developed applications over the last week-plus, I've been pleased to discover the many creative uses folks have come up with for this particular piece of silicon. Look for a post dedicated to elaboration of this point to appear soon on the?Brian's Brain?blog.
The lower-right corner of the image reveals the headphone jack, more accurately described as the headphone and?microphone?jack?in this product generation. No?dock-based workaround?is required for microphone functionality this time! Now all you need to do is wait for an?Apple-approved VOIP program?to appear on the App Store...that is, unless you alternatively just want to?jailbreak your iPod Touch...
Here's the lower end of the back-side assembly, again clearly showing the headphone/mic jack and dock connector.
The rectangular brown item in the middle of the photo is the speaker, new to the second-generation design. Remove it...
...and many of the device's primary silicon building blocks become visible. In the middle is the NAND flash memory, this particular one supplied by Micron, judging from the markings (prior Apple analyses by me have revealed Samsung- and Toshiba-sourced NAND flash memories). My iPod Touch is a 16-Gbyte model but, as the IC's part number suggests, iFixit took apart an 8-Gbyte (64-Gbit) unit. Note, too, that this is a multilevel-cell flash-memory device, not a higher-reliability (albeit higher cost-per-bit) single-level-cell flash memory as I've seen Apple use in the past. To the right of it is the Apple-marked ARM CPU. I'd be shocked if it wasn't the exact same Samsung model, with stacked DRAM included, as the one used in the?3G iPhone whose iFixit teardown I analyzed back in mid-July.
Below the CPU is what at first glance (judging from what I interpreted to be a firmware code sticker) I thought was an iPhone-reminiscent NOR flash memory-plus-PSRAM combo chip. However, since there's no cellular baseband processor in an iPod touch, and since the 8-Mbit Atmel flash memory to the right of the CPU houses the system boot code, I quickly realized that my first guess was erroneous. Portelligent's Carey set me straight; it's a power-management controller (which was my second guess—really!). The IC in the lower left-hand corner of the NAND flash memory is, I believe, the audio codec, whose vendor and specific product identity is obscured by Apple markings. Rumor has it that this chip doesn't come from?Wolfson Microelectronics, which supplied the bulk of Apple's iPod-plus-iPhone codec needs to date; are congratulations to?Cirrus Logic?(which also sources the codec in the iPod classic) in order?
Now let's take a look at the upper end of the iPod touch internal assembly. Front side first.
Remember the mysterious grey rectangular area I mentioned before? Underneath the RF-shielding lid, and shown in this photograph, is the combination of the touchscreen controller and the backlight control (data-fed by the adjacent ambient-light-sensor connector) circuitry.
Finally, let's have a gander at the upper end of the back-side assembly.
Once again, prying off the top of the RF shield reveals silicon inside, specifically a?Broadcom?Wi-Fi-plus-Bluetooth combo IC. This sourcing decision marks an interesting shift for Apple, since both iPhone generations along with the first-gen iPod touch employed?Marvell?Wi-Fi transceivers (along with?CSR-sourced Bluetooth ICs on the iPhones).
But here's the?really?curious part: The?second-generation iPod Touch feature set?currently doesn't include?any?mention of Bluetooth capability. What's a Bluetooth-capable chip doing in the design, then? At the moment, I suspect that the?Broadcom BCM4325?is implementing the?proprietary 2.4 GHz Nike+ peripheral protocol?(support for which is new to this iPod Touch generation). Long term, though, I'm hopeful that firmware upgrades will add true Bluetooth features to the platform; theBCM4325's documented support for A2DP "stereo" Bluetooth audio?would be particularly welcomed.
One other aspect of the Broadcom BCM4325 bears mentioning. In addition to Wi-Fi and Bluetooth, the chip?also?supports FM reception. Apple historically has been cool (at least publicly) to the idea of adding radio functions to its iPods, whereas?key hardware opponents such as Creative Labs, Microsoft and Sandisk?have supported the feature for years. Could competitive pressure compel Apple to mimic its peers either in the general sense (if for no other reason than to enable iPod-toting health club members to be able to listen to FM-transmitted television soundtracks) or, heaven forbid, even by matching the?purchase-from-radio feature Microsoft included with the latest Zune 3.0 update? It wouldn't be the?first time Apple's hand was (presumably) forced by the competition..
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