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.
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Optimized for Quasi-Resonant Converter (QRC)
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Low EMI through Variable Frequency Control and AVS(Alternating Valley Switching)
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High-Efficiency through Minimum Voltage Switching
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Narrow Frequency Variation Range over Wide Loadand Input Voltage Variation
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Advanced Burst-Mode Operation for Low StandbyPower Consumption
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Simple Scheme for Sync Voltage Detection
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Pulse-by-Pulse Current Limit
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Various Protection functions: Overload Protection(OLP), Over-Voltage Protection (OVP), Internal ThermalShutdown (TSD) with Hysteresis, Output ShortProtection (OSP)
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Under-Voltage Lockout (UVLO) with Hysteresis
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Internal High-Voltage Sense FET (650V)
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Built-in Soft-Start (17.5ms)
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