FL7733A: Primary-Side-Regulated LED Driver with Power Factor Correction

The FL7733A is a highly-integrated PWM controller with advanced Primary-Side Regulation (PSR) technique to minimize components in low-to-mid-power LED lighting converters.

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% over the universal line voltage range to meet stringent LED brightness requirements.

By minimizing turn-on time fluctuation, high power factor and low THD over the universal line range are obtained in the FL7733A. An integrated high-voltage startup circuit implements fast startup 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).

Features

• < ±3% Total Constant Current Tolerance Over All Conditions
• < ±1% Over Universal Line Voltage Variation
• < ±1% from 50% to 100% Load Voltage Variation
• < ±1% with ±20% Magnetizing 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 V_AC - 308 V_AC
• High PF of > 0.9, and Low THD of < 10% Over Universal Line Input Range
• Fast < 200 ms Start-up (at 85 V_AC) using Internal High-Voltage Start-up with V_DD Regulation
• Adaptive Feedback Loop Control for Startup without Overshoot
• LED Short / Open Protection
• Output Diode Short Protection
• Sensing Resistor Short / Open Protection
• V_DD Over-Voltage Protection (OVP)
• V_DD Under-Voltage Lockout (UVLO)
• Over-Temperature Protection (OTP)
• All Protections are Auto Restart (AR)
• Cycle-by-Cycle Current Limit

Application Notes