ST raises reliability and efficiency for ultra-compact LED lamps

GENEVA, SWITZERLAND: The first in a new family of mains-operated LED lamp drivers from STMicroelectronics, a global leader serving customers across the spectrum of electronics applications and the worldwide leader in ICs for electronic lighting control, will enable designers to deliver more reliable and efficient LED retrofit lamps featuring primary-side current regulation.

LED lighting, including retrofit bulbs, is expected to account for 80% of the lighting market by 2020 or sooner. Primary-Side Regulation (PSR) cuts bill-of-materials costs for retrofit bulbs, thereby reducing the payback time, while also simplifying design and reducing the space occupied by LED control circuitry.

The new HVLED805 integrates an 800V avalanche-rugged MOSFET, achieved using ST’s high-voltage integration process, which is higher than in competing devices and hence offers greater reliability. The high-voltage on-chip startup circuitry allows the device to start reliably when the AC line voltage is applied to the lamp.

Primary-side regulation maintains the constant LED current that is needed to ensure consistent light output, without requiring the current-sensing components and opto-coupler used in conventional secondary-side regulation. The elimination of these components decreases the cost and size of the LED driving circuitry and saves current-sensing losses, improving overall efficiency.

Using PSR, the HVLED805 guarantees LED current regulation to within 5% accuracy. Reliability is also enhanced, due to the elimination of the opto-coupler in the secondary side, whose degradation can significantly decrease the mean-time-between-failure of the lamp.

The HVLED805 PSR controller integrates high-voltage startup for efficient power-on, and the robust 800V power MOSFET allows a reduction of the snubber network. The highly efficient quasi-resonant (QR) operating mode further boosts energy savings for LED lighting and dramatically reduces the EMI filtering required, saving space and costs.