HF300 300kHz Ideal-Clamping Flyback Controller TSOT23

HF300 300kHz Ideal-Clamping Flyback Controller TSOT23

The HF300 is an intelligent, high-frequency, flyback, ideal clamping controller that is used to replace the passive resistor-capacitor-diode (RCD) snubber in a flyback circuit to clamp the drain-source voltage spike caused by the leakage inductance (LLKG) after the primary main switch turns off.

Key Specifications

Features

• Active-Clamp Drain-Source Voltage Spike
• Supports Continuous Conduction Mode (CCM), Discontinuous Conduction Mode (DCM), Quasi-Resonant (QR) Operation, and Zero-Voltage Switching (ZVS)
• Supports Up to 300kHz Switching Frequency (fSW)
• Easy to Use
• Extremely Low <5mW Standby Power Consumption
• Ultra-Wide VCC Range to Support USB PD Applications
• Intelligent Recycling Leakage Energy and Increased Flyback Converter Efficiency
• Under-Voltage Lockout (UVLO), Over- Current Protection (OCP), and Shoot- Through Prevention
• Available in a TSOT23-6 Package

Typical Application Circuit

Applications

• USB Power Delivery (PD)/Quick Charge (QC) Chargers and Adapters
• Adapters

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