Description In general, quasi-resonant converters (QRCs) show low EMI and high power conversion efficiency compared to conventional hard-switching converters with fixed switching frequency. Therefore, it is very suitable for QRC noisesensitive applications such as color TV and audio. Each product in the FSCQ series contains an integrated pulse width modulation (PWM) controller and a value SenseFET, and is designed specifically for quasi-resonant off-line switched-mode power supplies (SMPS) with minimal external components. The PWM controller includes an integrated fixed high frequency oscillator, undervoltage lockout, leading edge blanking (LEB), optimized gate driver, internal soft start, temperature compensated precision current source loop compensation and self-protection circuitry. Compared to a discrete MOSFET and PWM controller solution, the FSCQSeries can reduce overall cost, component count, size and weight while increasing efficiency, productivity and system reliability. These devices provide a basic platform that is well suited for cost-effective design of quasi-resonant flyback switching converters.

Features • Optimized Quasi-Resonant Converter (QRC)
• 1W standby power consumption under advanced burst mode operation • Pulse limited by pulse current • Overload protection (OLP patients) - automatic restart • Over Voltage Protection (OVP) function - automatic restart • Over Current Protection (AOCP) abnormal - Latch • Internal Thermal Shutdown (TSD) - Latch • Under Voltage Lockout (UVLO) function with hysteresis • Low startup current (typ: 25uA)
• Internal high voltage value SenseFET
• Built-in soft-start (20ms)
• Extended Quasi-Resonant Switching

Applications • AV Amplifier Related Application Notes • AN4146 - Quasi-Resonant Design Guidelines Converters Using FSCQ Series Fairchild Power Switches.
• AN4140 - Transformers for Offline Design Considerations for Flyback Converters Using Fairchild Power Switches.