Digital Diet Slims Your Power Designs

Jul 31, 2007 3:47 PM
By Lou Pechi, President, STRATA-Strategic Advisors, San Diego, Calif.

During the last 40 years, Moore’s Law has been the main driver for the power-supply industry. In 1965, Intel co-founder Gordon Moore noted that the power consumption of a chip doubles every 24 months. Later on, shifting into a higher gear, he accelerated his prediction to 18-month intervals. The demise of Moore’s law has been predicted for quite a while, due to the relentless addition of ever-smaller active devices, and the resulting leakage increase or “tunneling” through ever-thinner and narrower silicon insulation between the active devices on a chip. But recently, Intel, with its cleverness of replacing the silicon-dioxide isolation with the metallic alloy hafnium, dodged the demise of Moore’s law by another few years.

Like an enamored puppy, the power-supply industry has followed the Moore’s Law trend. Over the years, the industry has increased the power delivered by power supplies, while packing more circuits into their ever-decreasing physical size.

However, with efficiencies in the upper 90s, our industry also seems to be approaching a performance limit, and the end of further efficiency gains may be at hand. Frequent press releases laud every fraction-of-a-percent increase in efficiency as if this is the best that can be achieved. And, in all honesty, it probably is. We might approach the brass ring of 100% efficiency, but we’ll never quite reach the prize.

So, rather than continuing to ride the efficiency merry-go-round, let’s get off and explore other paths. And instead of concentrating all our efforts on stuffing more raw power into ever-smaller boxes, we need to put more brainpower into these already dense power supplies.

This shift is already happening gradually. From the introduction of simple on/off controls into board-mounted power supplies, we’ve progressed to overvoltage and overcurrent limiting, and remote output-voltage adjustments. However, these basic controls — tacked onto the proven analog circuitry on the board — started taking more and more space, reducing the overall power density of the supply.

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© 2007 Penton Media, Inc.