HFC0300 Variable Off Time Controller SOIC

HFC0300 Variable Off Time Controller SOIC

HFC0300 is a variable off-time controller that uses a fixed-peak–current technique to decrease its frequency as the load lightens.

Key Specifications

Features

• Variable Off-Time, Current Mode Control
• Universal Main Supply Operation (85VAC to 265VAC)
• Frequency Foldback as Load Lightens
• Peak-Current Compression to Reduce Transformer Noise
• Active-Burst Mode for Low Standby Power Consumption
• Internal High-Voltage Current Source
• Internal 200ns Leading Edge Blanking
• Thermal Shutdown (Auto Restart with Hysteresis)
• VCC Under-Voltage Lockout with Hysteresis
• Over-Voltage Protection on VCC Pin

Applications

• Battery Charger for Portable Electronics
• Standby Power Supply

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