●A Quasi-Resonant Converter (QRC) generally shows lower EMI and higher power conversion efficiency than a conventional hard-switched converter with a fixed switching frequency. The FSQ-series is an integrated Pulse-Width Modulation (PWM) controller and SenseFET specifically designed for quasi-resonant operation and Alternating Valley Switching (AVS). The PWM controller includes an integrated fixed-frequency oscillator, Under-Voltage Lockout (UVLO), Leading- Edge Blanking (LEB), optimized gate driver, internal soft-start, temperature-compensated precise current sources for a loop compensation, and self-protection circuitry. Compared with a discrete MOSFET and PWM controller solution, the FSQ-series can reduce total cost, component count, size, and weight; while simultaneously increasing efficiency, productivity, and system reliability. This device provides a basic platform for cost-effective designs of quasi-resonant switching flyback converters.
●Features
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● Optimized for Quasi-Resonant Converters (QRC)
● Low EMI through Variable Frequency Control and AVS (Alternating Valley Switching)
● High-Efficiency through Minimum Voltage Switching
● Narrow Frequency Variation Range over Wide Load and Input Voltage Variation
● Advanced Burst-Mode Operation for Low Standby Power Consumption
● Simple Scheme for Sync Voltage Detection
● Pulse-by-Pulse Current Limit
● Various Protection Functions: Overload Protection (OLP), Over-Voltage Protection (OVP), Internal
● Thermal Shutdown (TSD) with Hysteresis,
● Output Short Protection (OSP)
● Under-Voltage Lockout (UVLO) with Hysteresis
● Internal Startup Circuit
● Internal High-Voltage Sense FET (650 V)
● Built-in Soft-Start (17.5 ms)
