Offline Isolated Flyback LED Controller with Active PFC

The LT3799 is an isolated flyback controller with power factor correction specifically designed for driving LEDs. The controller operates using critical conduction mode allowing the use of a small transformer. Using a novel current sensing scheme, the controller is able to deliver a well regulated current to the secondary side without using an opto-coupler. A strong gate driver is included to drive an external high voltage MOSFET. Utilizing an onboard multiplier, the LT3799 typically achieves power factors of 0.97. The FAULT pin provides notification of open and short LED conditions.

The LT3799 uses a micropower hysteretic start-up to efficiently operate at offline input voltages, with a third winding to provide power to the part. An internal LDO provides a well regulated supply for the part’s internal circuitry and gate driver.

TRIAC Dimmable

LED Current Regulation

LT3799

YES

±10%

LT3799-1

NO

±5%

Applications

* Offline 4W to 100W+ LED Applications

* High DC VIN LED Applications

* Isolated PFC LED Driver with Minimum Number of External Components

* TRIAC Dimmable

* VIN and VOUT Limited Only by External Components

* Active Power Factor Correction (Typical PFC > 0.97)