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  Date: 26/04/2011

LED lighting circuit reference design from Power Integrations

Power Integrations has announced a new LED lamp reference design based on its single-stage LinkSwitch-PH LED-driver IC family. The new design eliminates the need for unreliable electrolytic capacitors and opto-isolators, making it especially well suited for high-reliability industrial, commercial, and exterior solid-state lighting (SSL) applications. Suitable for designs from 5 W to 55 W, SSL driver ballasts based on LinkSwitch-PH ICs achieve greater than 90% energy efficiency and satisfy the ENERGY STAR requirement of >0.9 power factor, says Power Integrations.

LED-based lighting systems have the potential for a much longer operational life than incandescent or fluorescent bulbs. However, the classical two-stage topology (i.e., power-factor plus high voltage DC-DC converter), which is sometimes used by manufacturers targeting consumer-grade bulb/lamp replacements, utilizes a high-voltage electrolytic bulk capacitor between the stages. The longevity of such systems is limited by the lifetime of the electrolytic capacitor, which tends to dry out and fail, particularly when situated in an enclosed space (e.g., a ballast "brick" or bulb base) and exposed to the heat produced by inefficient two-stage power conversion and proximal high-brightness LEDs, quotes Power Integrations. Power Integrations' LinkSwitch products eliminate both the electrolytic capacitor and the also-unreliable optocoupler used in traditional isolated flyback designs. Designers using LinkSwitch-PH ICs for SSL products can expect the operational life of the driver to exceed the 35,000 hours required by the ENERGY STAR SLL (V1.1) specification, according to Power Integrations.

Comments Doug Bailey, vice president of marketing for Power Integrations: "Municipalities, retailers, industrial users, and other businesses are finding that the upfront investment in LED lighting is more than justified by the combination of energy savings plus lower maintenance expenses resulting from the longevity of LED lights. However, the degree to which these benefits are realized depends heavily on the choice of driver technology. The two-stage drivers used in many residential replacement bulbs may not be adequate for applications in which maintenance savings are critical to the ROI calculation."

Bailey continues: "Our single-stage LinkSwitch-PH family eliminates the weak links in a typical LED driver. Using LinkSwitch-PH LED driver ICs alongside highly stable ceramic capacitors, designers can produce efficient, safe, cost-effective lighting systems that outlast SSL installations using consumer-grade drivers and save on costly maintenance."

LinkSwitch-PH ICs information is available at

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