In this case, it's the so-called flat-transformer technology, a one-turn multicore alternative to traditional single-core, N-turn planar components. "This technology is going to be hot for dc/dc converters," Mohan Mankikar, the energetic former author of this column, exclaimed recently. And when he gets that excited, especially after he's tracked the field for a long while, I listen.

In fact, the technology is here now, and there's plenty to be excited about. The flat transformer reduces leakage inductance by a factor of N2, easing the way for high-frequency (several MHz) operation. Heat generation is less because of the single winding, and so is overall size. Yet current densities are higher and power levels to 1.2 kW can be had in a full brick.

It's been a long road for the technology's owners, BTC Power Electronics, a joint venture of Behavior Tech Computer (Taiwan) and the Flat Transformer Technology Corp. (FTTC; Costa Mesa, Calif.). That may have been the result of system design engineers' rather surprising reaction to stay away from something too new, notes James Lau, FTTC's president. Thus BTC's philosophy was cast: Instead of licensing the transformer technology, demonstrate it with practical, commercially available converters.

Flat transformers won't "replace" well-established planar transformer technology. But there are advantages at the higher powers (>150 W), lower-voltage, higher-current applications, and for switching frequencies exceeding 250 kHz. BTC already has released a 200-W dc/dc model; 400 W is coming in March and a 960-W full brick is targeted for year's end. If that's realized, it is a substantial advance on the traditional 600-W converters now available.

When it comes to flat transformers most engineers apparently tired of analyzing the glamourless, classical transformer model, overlooking its potential. But the sun never sets on the basics: applying them is precisely the way to some of our greatest advances.