New LinkSwitch-PH 7.4-W LED driver reference design delivers better than +/- 2% CC accuracy

April 18, 2012
Date Announced: 18 Apr 2012 PI's new LED reference design (DER-296) describes a non-isolated, TRIAC dimmable LED driver with a power factor greater than 0.9. The design is optimized for a nominal LED string voltage of 66 V at 110 mA and uses high-line 176 VAC to 265 VAC input range. The LED driver utilizes the LNK403EG from the LinkSwitch-PH family of ICs and easily fits inside an A19 form factor.Key features and benefits include: •TRIAC dimmer compatible o>1000:1 dimming range (TRIAC dependent)oClean monotonic start-up – no output blinkingoFast start-up (<300 ms) – no perceptible delay•Low cost, low component count and small footprint solution oNon-isolated approach simplifies transformer construction; removes bias windingoExcellent output regulation, <1% typicaloFrequency jitter means smaller, lower cost EMI filterThe topology used is a single-stage non-isolated flyback that meets the stringent space requirements for this design. Enhanced line and load output current regulation requirements are achieved by using a sensing resistance and shunt regulator.

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