SAN JOSE, Calif. — Power Integrations Inc. believes its newly-introduced LinkSwitch single-chip switching power supply will help replace transformer-based linear power supplies with more compact, efficient switcher-based designs in the 1-to-3-watt range.

Bulky linear power supplies account for almost 10 percent of all residential energy consumption, according to Power Integration president and chief executive officer Balu Balakrishnan, and fall into the broad class of devices described as energy "vampires" by President George W. Bush when he signed a presidential order last year requiring government agencies to use energy-conserving devices. Bush signed the order just a month after Balakrishnan showed how much power is wasted by standby supplies in a demonstration for President Bush and U.S. Energy Secretary Spencer Abraham.

In an oft-repeated demo, Power Integration shows a 9-volt, 300-mA transformer-based supply consuming 1.65 W at standby, while a switching supply with the same output consumes 200 mW.

Having pioneered the integration of power MOSFET drivers on the same die with switching regulator controllers, Power Integrations has led the way toward small-footprint switching power supplies. The efficiency of a switching power supply is almost an order of magnitude higher than of a transformer-based linear supply.

In the midst of a harsh downturn in the semiconductor industry, Balakrishnan projects Power Integrations will grow 10 to 15 percent this year on the strength of a relatively simple growth strategy: deliver the semiconductors that will help replace wall-mountable transformer-based power supplies with more efficient units.

Despite their efficiency, there are certain markets that switching regulator devices have not been able to penetrate. Because the efficiency of switching power supplies tends to drop at lower current levels, Power Integrations has heretofore had limited access to the 1-to-3-watt power supply market, where most of the transformer-based regulator energy vampires reside, the company said.

The LNK501 LinkSwitch device introduced this week is designed to close that gap in the lower power area. The LNK501 will accept an input from 85 to 265 volts, and output a constant current and constant voltage for dc-powered appliances and battery chargers.

The LinkSwitch integrates a 700-V MOSFET, pulse width modulator, startup circuitry, current limiting and safety shutdown circuitry with a patented 3.0-micron process. The device can make a complete offline switching regulator circuit with as little as 14 external components, the company said.

No-load standby power consumption of such a regulator is under 300 mW — the consumption recommended by the European Commission on Energy Consumption for supplies in 2005, and considerably less than the 1-W goal recommended by Bush's presidential order. Full load efficiency is better than 70 percent.