PDA-on-the-cheap gets down to basics

The Protege includes a phone book with name, number and e-mail functions; a scheduler with a world alarm clock and timer; a memo pad; a 12-digit calculator; and a conversion table. Password lock and auto power-off are also yours for the roughly $20 retail price hawked in the "As seen on TV" ads for the product.

The Chinese-made Protege is marketed by Allstar Marketing Group LLC-and probably others-with the actual ODM not apparent from any markings.

Typical of many products in this class, the Protege uses a single two-layer circuit board with glass-reinforced outer layers but a less-expensive phenolic core, to offer some dimensional stability while shaving costs. The lone chip that powers the appliance is wirebonded to the pc board and "glob topped" for mechanical protection. In a world where every penny counts, even device packaging can add unnecessary costs when chips are cheap and yield is high enough to forgo extensive test and rework.

A smattering of discrete components rounds out the design, which is powered by just three button cell batteries-adequate for the unit's miserly, sub-30-milliwatt power consumption. Inexpensive carbon-elastomer compression connectors link both LCD and touchscreen to the board traces, and a simple snap dome taped to the surface serves as the on/off button.

A hand-soldered watch crystal provides clocking for the system ASIC, itself more of a "smart memory" chip than processor-centric design. Most of the 15-mm2 die is dedicated to the 8 Mbytes of system memory.

A fairly large but low-resolution reflective monochrome LCD is one inferior aspect of the design, but the low-tech display does help keep touchscreen costs to a minimum.

The 12 screws used in final assembly would punish manufacturing costs were it not for inexpensive labor in China. As it is, hand assembly becomes less expensive than automation, and the estimated cost of goods sold for the Protege was about half of the $20 purchase price.

Going forward, expect the low end of the true PDA to look more and more like the Protege in both construction and cost. Look no further than the history of the scientific calculator for historical parallels.

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

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