Power supply makers get ready for tighter energy efficiency regs

Tougher Energy Star standards kick in next year. Some manufacturers may not be able to handle its more stringent mandates.

The latest round of energy efficiency standards for external power supplies will go into effect next year. But unlike previous standards, efficiency levels dictated by the new mandates, which power supply makers dub Level 6, could spell difficulties for power supply makers.

“We couldn’t just tweak the current design to get there,” said Andrew Johnson, product manager for external supplies, CUI Inc.“For Level 6, we had to look at the whole topology and rethink it. The redo involved everything from the transformer to the control IC.”

The new efficiency levels could come as a surprise to power supply users that aren’t closely monitoring Energy Star. “The impact on OEM customers is that they’ll soon have to swap out current models to Level 6. Foreign firms sending products into the U.S. also have to be aware of this,” said Johnson. “We’ve found that in the past, customers have been generally unaware of the changes when there have been transitions from one level to the next. Companies need to start planning now for these changes.”

CUI said it will be releasing Level 6 supplies this year, starting with desktop adapters up to 150 W. Though CUI is ready to field power supplies meeting the new mandates, company officials think the new efficiency benchmarks are tough enough to precipitate a shake out among power supply vendors. “Going from Level 4 to Level 5, suppliers could get by with minor tweaks of their product, such as adjusting dc core length. Level 6 is not as trivial and safety issues are more important as well,” Johnson said.

Level-6 regs expand the range of products that fall under the Energy Star efficiency mandate. Regulated products will now include multiple-voltage external power supplies and products with power levels exceeding 250 W. The new rules also boost active mode efficiency by 5%.

But the biggest change, at least in the eyes of power supply makers, is no-load efficiency. Level 6 boosts it from 0.5 W to 0.1 W in supplies up to 49 W. It is the higher no-load efficiency that power supply makers find tough to meet and could force the most changes in circuit design. “We are still working through the cost impact. It could be a 5 to 10% bump. The transformer on some of the bigger designs will require a slightly larger case,” said Johnson.

The new standard also categorizes power supplies as direct operation and indirect operation products. A direct operation product is an external power supply (EPS) that functions in its end product without using a battery. An indirect operation EPS is not a battery charger, but cannot operate the end product without the assistance of a battery. The Level 6 standard only applies to direct operation external power supplies. Indirect operation models will still be governed by the limits as defined by EISA2007.

U.S. supply makers designing products for export must wait to find out whether Level 6 will apply in other parts of the world. The EU and Canada currently are at Level 5 efficiency specs. Supply makers expect a ruling in the next year about whether they will go to the new levels.