Optoelectronics
New LED Driver Design from Power Integrations Maximizes Efficiency of High-Voltage LEDs, Targets Compact B10, GU10, E17 and A19 Bulbs
Power Integrations has published a reference design (DER-297) describing a high-efficiency, ultra-compact driver for a B10-style LED light bulb. Based on Power Integrations' LinkSwitch-PL non-isolated, single-stage LED driver IC, the power supply is specifically tailored for use with high-voltage LEDs such as the recently announced XLamp XM-L and XLamp XT-E ranges from Cree. DER-297 provides the high-voltage output required by the LEDs, optimizing overall system efficiency by reducing power lost due to current flow in the driver inductor and output diode.
The DER-297 power supply design is very small and cost-effective with a BOM of only 20 components. The high level of integration in the LinkSwitch-PL device combines PFC and constant-current functions into a single buck-boost stage requiring only a tiny inductor. The design reaches 87% efficiency at 115 VAC for a 4.3 W LED driver (86% for 2.9 W output) while achieving a power factor greater than 0.9, easily meeting EN61000-3-2 Class C limits, and creating less than 20% Total Harmonic Distortion (THD).Commented Andrew Smith, product marketing manager for LED applications at Power Integrations: The tiny B10 and similarly compact form factors are very challenging for LED lamps. The LinkSwitch-PL device used in DER-297 permits the driver to be both small and highly efficient, which allows us to pack the design into a B10 base without using potting compound or compromising performance. The simple BOM also means that the converter has a very low cost, making DER-297 ideal for this increasingly price-competitive market.
Mark McClear, applications engineering director at Cree, added: The very low-volume enclosure of the B10 bulb creates a substantial engineering challenge for the driver designer. Power Integrations' LinkSwitch-PL device configured in the buck-boost topology not only drives the LEDs beautifully, but easily meets the physical and thermal specifications due to the low component count and high operational efficiency.