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Fairchild Semiconductor's High Brightness LED Lighting Reference Design Reduces Design Complexity

 2009-06-15

Fairchild Semiconductor brings designers of LED applications a reference design that allows implementation of an AC-input LED lighting system without a secondary-side control circuit and optocoupler.  The RD226 is a universal input, 12W LED lighting solution that reduces both the size of the HB LED lamp and saves in bill of materials (BOM) cost.  This reference design features an isolated, primary-side regulated off-line AC-DC converter in flyback topology and offers a universal input voltage range of 85VRMS to 265VRMS at a line frequency of 50Hz to 60Hz. It has one constant current output, selectable between 350mA and 700mA both at a maximum output voltage of 17V. This reference design features Fairchild’s FAN102 device that is used as a primary-side-control PWM controller, reducing overall system cost and size. 

HB LED applications with an AC mains input, require an electronic circuit to convert the AC-input voltage into a constant current and in some applications, the load must be isolated from the mains input, requiring additional design complexity.  The traditional approach requires a flyback converter with a constant current output.  In most cases, a control circuit on the secondary side using an operational amplifier and a reference, or a dedicated control IC, regulates current and sends the control information to the PWM controller on the primary side via an optocoupler. Fairchild's innovative solution enables designers to implement AC input LED lighting system without the secondary side control-circuit and the optocoupler.

Fairchild offers a wide range of reference designs that reduce board space, simplify design, ensure system reliability and speed time to market. These production-ready designs are important in enabling OEMs to shorten their design time and bring their applications to market faster.

The RD226 reference design is available on Fairchild's website at http://www.fairchildsemi.com/support/referencedesign/index.html. To request a universal input lighting solution evaluation board (FEB226), please contact your local sales office.