LED current ripple suppressor

Diodes Incorporated announces the availability of the AL5822 LED current ripple suppressor, which provides high levels of ripple suppression while maintaining high power factor for commercial and industrial lighting applications.

It is now mandatory to meet regulatory requirements to suppress low frequency ripple (100Hz to 120Hz) in LED lighting applications in many markets, enforced through standards such as the California Energy Commission Title 24. 

The AL5822 delivers a high level of ripple current suppression in single-stage, high power LED installations, even when triac or PWM dimming techniques are being used to vary the light level. This ensures there is no sign of flicker or strobing across the entire dimming range, while still maintaining a high power factor. 

The AL5822 has been designed and tested to comply with the Title 24 building code requirement of less than 30% flicker. 

The results show that the AL5822 suppresses over 97% of ripple while still achieving a power factor of greater than 0.9. 

By monitoring the current flowing through the LEDs, the AL5822 compensates for ripple by adjusting the drive voltage for the external MOSFET. This control loop keeps the MOSFET operating in the saturation region to deliver a constant current. 

With support for various pre-stage circuits, the AL5822 can work with a number of drivers, such as the AL1665 single stage PFC flyback buck/boost controller, also from Diodes Incorporated. 

The integrated features of the AL5822 remove the need for magnetic discrete components, minimising the overall bill of materials. 

The AL5822 operates over an input voltage range of 24Vac to 305Vac. Safety features include LED short-circuit, over-temperature, and over-current protection.