FSCQ1265RT: 650V Integrated Power Switch for 140Watt offline flyback converters

A Quasi-Resonant Converter (QRC) typically shows lower EMI and higher power conversion efficiency compared to a conventional hard-switched converter with a fixed switching frequency. Therefore, a QRC is well suited for noise-sensitive applications, such as color TV and audio. Each product in the FSCQ series contains an integrated Pulse Width Modulation (PWM) controller and a SenseFET. This series is specifically designed for quasi-resonant off-line Switch Mode Power Supplies (SMPS) with minimal external components. The PWM controller includes an integrated fixed frequency oscillator, under-voltage lockout, leading-edge blanking (LEB), optimized gate driver, internal soft-start, temperature-compensated precise current sources for loop compensation, and self-protection circuitry. Compared with a discrete MOSFET and PWM controller solution, the FSCQ series can reduce total cost, component count, size, and weight; while increasing efficiency, productivity, and system reliability. These devices provide a basic platform for cost-effective designs of quasi-resonant switching flyback converters.

Features

• Optimized for Quasi-Resonant Converter (QRC)
• Advanced Burst-Mode Operation for under 1 W Standby Power Consumption
• Pulse-by-Pulse Current Limit
• Overload Protection (OLP) – Auto Restart
• Over-Voltage Protection (OVP) – Auto Restart
• Abnormal Over-Current Protection (AOCP) – Latch
• Internal Thermal Shutdown (TSD) – Latch
• Under-Voltage Lockout (UVLO) with Hysteresis
• Low Startup Current (Typical: 25 μA)
• Internal High Voltage SenseFET
• Built-in Soft-Start (20 ms)
• Extended Quasi-Resonant Switching

Application Notes