As recently as 2003 there were no mandatory regulations in place regarding energy consumption for power supplies. Then, from 2004 to 2007 a number of Level III standards were implemented in various guises throughout the US, China, EU and Australia, including the voluntary Energy Star efficiency program.
Between 2008 and 2012 this moved up a stage to Level IV standards, which included implementing phase one of the ErP Directive in the EU, as well as updates in Australia and to the Energy Star program. Level V bridged the gap between Level IV and the most up-to-date Level VI standards which were first published in 2014 and went into effect in the US in 2016.
The following regions and countries now have mandatory regulations in place that all external power supplies shipped over their borders must meet the specified levels:
Why is legislation changing so rapidly?
By the start of the 21st century, a vast mass of systems and devices used power supplies that weren’t designed to shut down when the device they were powering was inactive, so they continued to drain power as if feeding an active load. Power supplies can easily consume 1W, which if multiplied by the number of hours plugged in, plus the number of devices and systems left plugged in continually, adds up to a massive waste of energy. It was concerns about this ‘vampire’ power drain from live mains sockets that was the main focus of the ErP Directive.
For this reason, designers of external power supplies for consumer electronics and computers have come under increasing legislative pressures to increase energy efficiency over recent years. With no global standards, designers aim to comply with the most stringent standards available to ensure products are suitable to sell across international borders – currently that is the Level VI Efficiency Standard.
Power supply manufacturers must indicate the level of product compliance by placing the appropriate Roman numeral (IV, V or VI) on regulatory label of each power supply product as specified by the International Efficiency Marking Protocol for External Power Supplies Version 3.0. This makes it easy for consumers to check, buy and use the appropriate power supply.
Today’s design considerations
Power supply designers are challenged with finding new techniques to improve efficiency and support these increasingly stringent standards, and manufacturers of external power supplies such as XP Power, Mean Well and RS Pro offer a range of products that meet these demanding standards.
Designers of custom external power supplies, common in multiple-output units, need to consider load detection to cut the power to the absolute minimum when power isn’t needed, as well as advanced switched-mode power conversion techniques and the energy efficiency improvements these can achieve.
Power conversion controllers are getting more intelligent, such as onsemi NCP1271 which features ‘sleep’ and ‘pulse-skipping’ modes so when the activity load reduces, the PWM controller drops pulse cycles instead of supplying wasted energy. After a number of skipped cycles, a specialised controller, like the UCC28710 from Texas, can put it in a power-down mode that will disable switching entirely. Or, if the load restarts, the increased energy demand causes a voltage drop so the active PWM mode will take over.
Using USB as the data and power connector offers a way of detecting whether there is an active load, and can disable the power supply when the end device is disconnected from it.
No matter where you are in the world, whether designing custom power supplies or packaged adapters, you will no doubt be affected by the tightening of energy regulations because of the need to support products for a global market. These standards will surely continue to tighten, driving engineers to develop new techniques and find pioneering solutions – driving a further wave of innovation.
Check out our Power Management applications page on RS online to find out more
Dave from DesignSpark
