IC Circuit Adapts LED Lights to Triac-Based Dimmers

Fairchild Semiconductor introduced the FL7730 single-stage primary side regulation (PSR) controller with power factor correction (PFC) for triac and analog dimming compatibility. The FL7730 circuit is an active PFC controller for single-stage flyback topology application. The device supports both triac and analog dimming. The device can achieve triac dimming control without flicker over the full range of 0 to 100% light output. The FL7730 combines primary-side regulation and a single-stage PFC topology to minimize total bill-of-material (BOM) count, such as an input electrolytic capacitor and feedback circuitry, therefore allowing for a more compact, longer life, and lower system cost design. There is also an FL7732 for non-dimming applications.

To improve power factor and THD, both devices feature constant on-time control with an internal error amplifier and low bandwidth compensator. Precise constant current accuracy/control (± 5 percent) regulates accurate output current, independent of input and output voltage, allowing designers to achieve high and improved lighting quality. Operating frequency is proportionally adjusted by output voltage in both devices to guarantee DCM operation with optimized PF/THD and simpler design.

Power factor is ~0.9 with low total harmonic distortion (THD) (Class C). Power efficiency is up to 85 percent for the FL7730 and over 85 percent for the FL7732 in non-dimming applications. These characteristics allow these ICs to meet worldwide energy saving regulations.

1,000 quantity pieces:

• FL7730: $1.27
• FL7732: $1.15
• Availability: Samples available upon request.
• Delivery: 8-12 weeks ARO

Fairchild Semiconductor
Part Number: FL7730/2