Fairchild Simplifies Dimmable LED Lighting Design

Single-Stage Primary-Side-Regulation PWM Controller for PFC and Phase Cut Dimmable LED Driving

The FL7734 is a highly integrated PWM controller with advanced Primary-Side-Regulation (PSR) technique to minimize components for low power LED lighting solutions. Using the innovative TRUECURRENT technology for tight constant-current control, it enables designs with constant-current (CC) tolerance of less than ±1% in the wide line voltage range to meet stringent LED brightness requirements.

FL7734 can operate with all types of phase cut dimmers. Phase cut dimming is managed smoothly by bleeding current control to achieve excellent dimmer compatibility without flicker.

Fairchild Simplifies Dimmable LED Lighting Design

The controller can automatically detect whether there is a dimmer connection. In non dimming mode, the operating mode is set to optimize power factor and THD by enabling linear frequency control and voltage mode based on DCM.

An external high-voltage bleeding circuit is utilized to implement fast startup and high system efficiency. The FL7734 also provides powerful protections, such as LED open / short, sensing resistor shorted, and over-temperature for high system reliability. The FL7734 is available in 16-pin Small-Outline Package (SOP).


  • Excellent Dimmer Compatibility by Active Dimming Control
  • Programmable Dimming Curve and Input Current Management
  • Constant LED Current Regulation in Large Phase Angle Range
  • Cost-Effective Solution without Input Bulk Capacitor and Feedback Circuitry
  • Accurate Constant-Current (CC) Control, Independent on Line Voltage, Output Voltage, Magnetizing Inductance Variation
  • Power Factor Correction (PFC)
  • Fast Startup utilizing Bleeding Circuit
  • Open-LED Protection
  • Short-LED Protection
  • Sensing Resistor Short Protection
  • Cycle-by-Cycle Current Limiting
  • Over-Temperature Protection with Auto Restart

For more detail: Fairchild Simplifies Dimmable LED Lighting Design

About The Author

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough research and presenting information in a structured and logical format.

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