Fast-Recovery Diodes Boost PFC Performance in High-Power LED Lighting

As power LEDs penetrate lighting applications from room lighting all the way to street lamps rated above 300W, those above 25W requiring mandatory PFC can use Fairchild Semiconductor’s STEALTH™ II and Hyperfast II diodes for optimum efficiency.

Normally, a boost-PFC stage is inserted between the line input and the LED power controller to prevent interference being put onto the supply line. Fast-recovery diodes are needed to reduce EMI and save MOSFET switching losses in the boost PFC, and Fairchild’s two diode families enable the most cost-effective solution at low or high power levels.

For applications up to 200W, where Boundary Conduction Mode (BCM) PFC is preferred, the FFPxxH60S Hyperfast II diodes have the lowest possible forward voltage to minimise conduction losses. Reverse-recovery time up to 45ns is ideal for BCM circuits, where fast and soft reverse-recovery is not needed.

Continuous Conduction Mode (CCM) is employed at higher power ratings, and requires fast reverse-recovery and soft-recovery characteristics to reduce MOSFET switching losses and EMI. Fairchild’s FFPxxS60S STEALTH II diodes are the optimum choice for CCM PFC, offering faster reverse-recovery time and 2.6V forward voltage.

 

FEATURES High reverse voltage High reliability Low stored charge Avalanche-energy rated

APPLICATIONS PFC for LED lighting Freewheeling diode for motor drives Power-switching circuits General SMPS

 

 

 

Fairchild Semiconductor / STEALTH II