Power Supply Reference Design Enables 10mW No-load Consumption

The EuP standard will limit standby power consumption to 500 mW, and many eco-minded manufacturers of consumer products and appliances are choosing even lower standby power budgets of 100 mW, 50 mW, or even 30 mW. A standby power supply that consumes only 10 mW at zero load allows a greater margin for other leaky circuit components, such as input filters, capacitors, and bias components, while still providing the power required to support valuable system standby activities. These include functions such as powering circuits to monitor an infrared remote control in consumer entertainment equipment, as well as hardware to sense a key-press to activate appliances or send automated wake-up signals such as those provided to an LCD monitor by a PC.

The power circuit described in DER-227 is based on Power Integrations’ LNK363DN, a member of the LinkSwitch-XT offline switcher IC family in an SO-8 package. This 3-watt, single-output, isolated power supply operates from a universal 85 to 265 VAC input, delivering 5 V at up to 0.6 A. It meets EN55022B/CISPR22B limits without the need for a Y capacitor, and meets the efficiency requirements of the European EuP Ecodesign Directive and ENERGY STAR EPS v 2.0.

Comments Andrew Smith, product marketing manager at Power Integrations: “Consumers are increasingly interested in green products. In response, equipment manufacturers are developing products that use energy more efficiently and the market is moving rapidly towards exceptionally low power use, particularly in standby mode. Our EcoSmart technology meets this need by drastically reducing power consumption in no-load and light-load conditions.”

Smith continues: “The power supply described in DER-227 also features careful transformer design and circuit bias component selection, combined with algorithms that switch only when required to maintain output voltage regulation, facilitating extremely low power consumption. This allows the supply to deliver power to the system immediately when it turns on, while consuming very little power itself.”