Entry-level PDA bucks CPU trend

The design, first introduced a year ago, builds from Samsung's 266-MHz S3C2410X RISC processor, based on an ARM920T core. Along with 16 Mbytes each for instruction and data cache, the Samsung part integrates an external memory controller, provides a NAND boot loader and implements the expansion memory interface for external Secure Digital and MultiMediaCard data cards. An on-chip LCD controller allows direct interface to the iPAQ's handsome 320 x 240-pixel TFT transflective display from Sony.

Given the S3C2410X processor's focus on handheld markets, additional functions have been rolled on-chip in an effort to lower external component count. An eight-channel, 10-bit A/D converter handles voice capture and the resistive touch panel leverages a built-in touchscreen controller. Internal circuits for system clock generation are also included. Attention to power consumption led Samsung to offer four modes of operation ranging from wide awake to power off, with various portions of circuitry mapped out or turned off to effect less drain. Memory voltages from 1.8 to 3.3 V are supported while core voltage is fixed at 1.8 V.

A Philips UDA1380 combo stereo codec and headphone amplifier combined with a National Semiconductor LM4890 audio power amp deliver the audio goods. System memory comes in the form of two Infineon 32-Mbyte SDRAMs (the HYB39L256160AT) and a 32-Mbyte NAND flash from Toshiba (TC58DVM82A1FTIO).

Despite its entry-level positioning, wireless connectivity has been engineered into the iPAQ 1945, thanks largely to Bluetooth component-count and cost reductions. A ceramic module manufactured by Zeevo of Taiwan carries both a single-chip Bluetooth baseband-transceiver (TC2000C2) and an SST 512-kbyte flash memory (SST39VF400A).

Even with all the integration, system implementation demands a surprising level of digital and analog glue. A host of components are used for power functions, and the circuit board's landscape is dotted with single-gate logic chips (more details are available at www.planetanalog.com/showArticle.jhtml?articleID=16101399). It seems that ASIC integration has yet to fully address the quickly evolving designs and uncertain volumes of the handheld market. As a result, a meaningful portion of the iPAQ's $100 bill of materials still goes to a group of smaller device players.

David Carey is president of Portelligent Inc. (www.teardown.com). The Austin, Texas, company produces teardown reports and related industry research on wireless, mobile and personal electronics.

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