In the primary role of GPS processing, an STA5620 single-chip RF front end from STMicroelectronics demodulates and converts RF signals from the internal 25 mmsq. ceramic block patch antenna. Because there are fewer form-factor constraints than would be found with GPS in a cellphone--for example, the largish antenna can still be tucked into the product, offering better gain than a small stamped-metal aerial. A Maxim Integrated Products LNA fronts the receiver chip to further enhance signal-to-noise ratios for fast time- to-fix.
Signals from the RF receiver pass to the largest device, a Garmin-ST-marked processor that handles the GPS correlator functions along with system control and peripheral support. The Garmin-branded package has many of the physical attributes and similar functional attributes of STMicroelectronics's ARM-powered STA2062 "Cartesio" device, an obvious possible companion to the ST RF front end. Speech synthesis, LCD control, microcontroller functions, USB and memory interfaces are all cooked right in.
System memory for the processor comes from 32 MB of DDR SDRAM from Hynix (for working memory) and 2 GB of iNAND flash from Sandisk. The latter holds all mapping data and system code (for download to DDR SDRAM) with the inclusion of a NAND controller to manage the host processor interface. Wear-leveling and error correction along with SD or SPI bus interface formatting are all handled in the controller chip, co-packaged with what is almost certainly multilevel-cell (MLC) NAND silicon.
Outside of the GPS and storage buckets, the remaining parts serve analog functions of the system. A Linear Technology LTC35571 takes care of USB battery charging and DC-DC conversion needs, with a second Linear part--the LT3591--rounding out power management for the white LED backlighting of the Sharp-manufactured LCD touchscreen module. A TI TSC2046 serves as the touchscreen controller and TI also supplies the two chips comprising audio functions with a stereo DAC (PCM1774) and audio power amplifier (TPA2010).
For every new price/function barrier broken, there tends to be a new wave of buyers, and Garmin seems intent on capturing the price-sensitive customer. As full-enough featured PNDs come in below the $200 price point and show up en-masse on retail racks, the next obvious question for Garmin and all its competitorsis: How long until $100?
David Carey is president of Portelligent, a TechInsights company that produces teardown reports and related industry research on wireless, mobile and personal electronics (www.teardown.com).
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