HFC0511 Fixed-Frequency Flyback Controller SOIC8

HFC0511 Fixed-Frequency Flyback Controller SOIC8

The HFC0511 is a fixed-frequency, current- mode controller with internal slope compensation specifically designed for medium-power, offline, flyback, switch-mode power supplies.

Key Specifications

Features

• Fixed-Frequency, Current-Mode Control with Internal Slope Compensation
• Frequency Foldback down to 27kHz at Light Load
• Burst Mode for Low Standby Power Consumption, Meeting EuP Lot 6
• Frequency Jitter to Reduce EMI Signature
• X-Cap Discharge Function
• Adjustable Over-Power Compensation
• Internal High-Voltage Current Source
• VCC Under-Voltage Lockout (UVLO) with Hysteresis
• Brown-Out Protection on HV
• Overload Protection with Programmable Delay

Typical Application Circuit

Applications

• AC/DC Power for Small and Large Appliances
• AC/DC Adapters for Notebook Computers, Tablets, and Smart Phones
• Offline Battery 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