HFG611-45 High-Frequency Quasi-Resonant Flyback Regulator QFN-21

HFG611-45 High-Frequency Quasi-Resonant Flyback Regulator QFN-21

The HFG611-45 is a quasi-resonant (QR) flyback regulator with an integrated GaN FET, which is suitable for the high-performance and high-frequency designs.

Key Specifications

Features

• Integrated 700V/300mΩ GaN FET
• Novel Patented Quasi-Resonant (QR) Control to Eliminate Audible Noise
• Ultra-Wide Supply Voltage (VCC) Range to Support USB Power Delivery (PD) Applications
• Built-in X-Capacitor Discharger
• Built-In High-Voltage Start-Up Circuit
• Ultra-Low Standby Power Consumption with PD Protocol IC (<30mW)
• Peak Current Mode Control and Leading- Edge Blanking (LEB)
• Available in QFN-21 (5mmx6mm) and QFN- 25 (7mmx7mm) Packages

Typical Application Circuit

Applications

• Cellphone Chargers

Design Notes

• The PFC inductor must support the maximum duty cycle at the lowest line voltage, which is where saturation risk peaks.
• High-voltage startup and X-capacitor discharge paths dominate no-load standby loss; verify them against the efficiency target.
• Leakage inductance and the RCD clamp set the turn-off loss — snubber values are a thermal trade-off, not a fixed recipe.
• Synchronous rectification timing must track the primary switching; a mistimed SR FET conducts through its body diode and fails hot.

Common Questions