The LinkSwitch-II family of power-conversion ICs from Power Integrations has some bragging rights, as it has achieved the recently announced five-star rating for no-load energy consumption. Launched by the world’s top five cell-phone manufacturers last month, the rating system covers all chargers sold by Nokia, Samsung, Sony Ericsson, Motorola, and LG Electronics. Efficiency ratings range from five stars for the most efficient chargers down to zero stars for the worst energy hogs.

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If left plugged into an electrical outlet, cell-phone chargers keep using electricity even when they’re disconnected from the phone. The coveted five-star rating goes to chargers that don’t exceed 0.03 W (30 mW) of power consumption in no-load mode, which can account for up to two-thirds of the electricity used by mobile phones. In fact, cell-phone manufacturers say that if the 3 billion mobile devices in service today all used four-star (0.03 to 0.15 mW) or five-star chargers, the world would save energy equal to the yearly output of two mid-sized power stations.

With the LinkSwitch-II devices, according to Power Integrations, manufacturers can achieve the five-star rating and meet other efficiency specifications like Energy Star 2.0 without increasing the cost of their chargers. The ICs use the company’s EcoSmart technology to automatically adjust power consumption when the charger enters a no-load condition. They also eliminate the need for optocouplers and secondary-side CV/CC control circuitry, as well as all control-loop compensation circuitry. This reduces component count by as much as 30% while improving energy efficiency since secondary-side components consume power.

“People may not realize that if they leave their cell-phone charger plugged in, which most people do, it may consume up to 0.5 W even when disconnected from the phone. The new star rating system makes it easy for consumers to compare and choose the most energy-efficient chargers,” said Doug Bailey, vice president of marketing at Power Integrations. “LinkSwitch-II enables designers to slash overall component count and eliminate lossy components such as the sense resistor.”

• Power Integrations

The LinkSwitch-II family of power-conversion ICs can help mobile-phone chargers achieve the five-star energy efficiency rating by sipping less than 0.03 mW in no-load mode.

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