The message seems clear: When it comes to power distribution for ever-evolving data, telecom, industrial systems and the like, the industry won't be converging on one standard for the intermediate-bus voltage. Nor will there be a universal maxim dictating architectural form for the advanced point-of-load (POL) dc/dc converters that power these systems, the recent alliance of Artesyn, Astec and Texas Instruments notwithstanding.

There are just too many market segments, and with complexity will still come confusion. Incredibly, there's often not even agreement on placing a point-of-load converter right at the load to maximize efficiency, which is supposedly the reason for the POL's existence. All of this means varying bus voltages, new sublevel power bus architectures, more bus designs hugging the 3.3- and 5-volt regions, and step-up converter topologies driven from those lower bus voltages to power systems, just to name a few.

"People would have you think there's a standards push for a 12-V bus, or a 7- to 9-V bus or whatever, but none of that is even remotely true," says one industry observer. "What's going to define the bus is the application." Vendors need to operate in an environment that encourages compatibility but at the same time puts some distance between their product and the competitors'. And when it comes to dc/dc converters, only so much is in the vendors' control. That's because today's demands for expanding functionality in PC and microprocessor-based systems are launching power structures in directions that are often ill-defined, seemingly unlimited in number and form and, occasionally, independent.

So expect more customization, not necessarily standardization, as a consequence of diversification. Bus structures, and the POL converter solutions for servicing the 50-watt-and-below region in particular, are still wide open. Multichip module, standalone IC, discrete converter-they're all used, and none yet demonstrate an edge that would have designers flocking to one over another.

Device-wise, we've seen the first monolithic 3.3-V step-up IC with a fair amount of current delivery for powering 5-V systems. Other outgrowths of customization could well include a wide range of dc/dc chips that are truly self-contained-that is, having no external components whatsoever, yet delivering much greater power. The whole of the development picture creates issues, but for the moment only for those of us who need to explain what it all means to the designer.