The third-generation model of Apple’s popular iPhone debuted last month with a feature set and bill-of-materials (BOM) that’s very similar to its predecessor. Yet a dissection of the 3G S conducted by the iSuppli Corp. Teardown Analysis Service reveals key changes in parts and suppliers.

The entry-level, 16-Gbyte version of the iPhone 3G S has a $172.46 BOM and a $6.50 manufacturing expense for a total cost of $178.96. This is slightly higher than the $174.33 that iSuppli estimated for the original low-end 8-Gbyte iPhone 3G based on pricing in July 2008. The total does not include costs such as software development, shipping and distribution, packaging, royalties, and accessories.

“Although the retail price of the 16-Gbyte iPhone 3G S is $199, the same as for the 8-Gbyte version of the original iPhone 3G, the actual price of the phone paid by the service provider is considerably higher, reflecting the common wireless industry practice of subsidizing the cost of a mobile phone and then making a profit on subscriptions,” said Andrew Rassweiler, director and principal analyst of teardown services at iSuppli.

In addition to faster performance, the 3G S improves upon the original 3G with video capture, an autofocus 3-Mpixel camera, and a built-in digital compass. Despite these extras, though, the 3G S hardware set isn’t that different fro the 3G. According to Rassweiler, Apple leveraged this commonality to optimize materials costs.

Furthermore, he said, the price erosion in the electronic component marketplace enables Apple to provide a product with more performance and memory with only a slightly higher materials and manufacturing costs. Still, Rassweiler noted, there are a few key differences in component selection compared to the iPhone 3G introduced a year ago.

For example, the 3G S uses a Broadcom single-chip Bluetooth/FL/WLAN device that costs $5.95, representing the industry trend of higher integration. The previous 3G used a Marvell Technology Group WLAN chip and a Cambridge Silicon Radio Bluetooth IC to implement these functions.  Also, the 3G S uses a Dialog Semiconductor power-management IC that costs $1.30 and replaces the NXP Semiconductors device in the 3G.

The digital compass in the 3G S uses an AKM Semiconductor electronic compass and an STMicroelectronics accelerometer, both of which are three-axis devices. The STMicro part determines device orientation or inclination, while the AKM sensor detects device movement relative to magnetic north. These additions support the 3G S’s ability to orient a map on the screen to correspond with the direction the user is facing.

While some analysts expected Qualcomm to displace Infineon Technologies AG as the supplier of the phone’s baseband chip, the 3G S uses Infineon’s PMB8878, which accounts for $13 of the component costs. TriQuint also continues to supply the power- amplifier module, supporting the phone’s tri-band HSPA functionality.

Toshiba had the biggest single design win in the 3G S, with its $24 16-Gbyte multilevel-cell (MLC) NAND flash. As NAND flash pricing has risen over the past few months due to supply constraints, this represents a lucrative achievement. But while Toshiba supplied the NAND in the specific 3G S that iSuppli dissected, the part also is available from other likely Apple suppliers, most notably Samsung Electronics Co. Ltd.

Samsung also continued to supply the iPhone’s applications processor, which costs $14.46 and is the fourth most costly component in the 3G S after the NAND flash, the display module, and the touchscreen assembly. The processor is key to the 3G S’s faster performance. While the 3G used an ARM RISC microprocessor with 40-MHz clock speed, the 3G S uses a 600-MHz version.