New LED Phase Cut Dimmer IC


Meeting the demand of LED market, Fairchild has announced the launch of new phase-cut dimmable single- Stage LED Driver IC by using an innovative TRUECURRENT technology to provide tight tolerance constant-current output, this LED driver enables designs with constant current (CC) tolerance of less than ±1 per cent over the universal line voltage range to meet stringent LED brightness requirements.

According to the media release, “The FL7733A is a highly-integrated PWM controller with advanced Primary-Side Regulation (PSR) technique for minimising components in low-to-mid-power LED lighting converters. By minimising turn-on time fluctuation, high power factor and low THD over the universal line range are obtained in the FL7733A. An integrated high-voltage start-up circuit implements fast start-up and high system efficiency. During startup, adaptive feedback loop control anticipates the steady-state condition and sets initial feedback condition close to the steady state to ensure no overshoot or undershoot of LED current. The FL7733A also provides powerful protections, such as LED short / open, output diode short, sensing resistor short / open and over-temperature for high system reliability. The FL7733A controller is available in an 8-pin Small-Outline Package (SOP).”

The key features and specifications of FL7733A are as below:

  • 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, Magnetising Inductance Variation
  • < ±3 per cent Total Constant Current Tolerance Over All Conditions
  • < ±1 per cent Over Universal Line Voltage Variation
  • < ±1 per cent from 50 per cent to 100 per cent Load Voltage Variation
  • < ±1 per cent with ±20 per cent Magnetising Inductance Variation
  • Primary-Side Regulation (PSR) Control for Cost-Effective Solution without Requiring Input Bulk Capacitor and Secondary Feedback Circuitry
  • Application Input Voltage Range: 80 VAC – 308 VAC
  • High PF of > 0.9, and Low THD of < 10 per cent Over Universal Line Input Range
  • Fast < 200 ms Start-up (at 85 VAC) using Internal High-Voltage Start-up with VDD Regulation
  • Adaptive Feedback Loop Control for Startup without Overshoot


Please enter your comment!
Please enter your name here

Are you human? *