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Fairchild Power Switch(FPS) TV Solution Power Conversion. Features and Advantages of FSCQ-series. Features Optimized for Quasi-resonant converter (Low EMI and High Efficiency) Fully avalanche rated and 100% tested SenseFET Pulse-by-pulse current limiting
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Features and Advantages of FSCQ-series • Features • Optimized for Quasi-resonant converter (Low EMI and High Efficiency) • Fully avalanche rated and 100% tested SenseFET • Pulse-by-pulse current limiting • Improved reliability through various protection functions • Over voltage, Over load, Over current, Thermal shutdown • Advanced Burst operationfor low power consumption in standby (<1W) • Internal Soft start function (20ms) • Extended Quasi-resonantoperation for wide operation range • Reduced startup and operating currents • Advantages • Reduced board space (simple & compact circuit design) • Decreased assembly time and field failure rate Enhanced productivity
FSCQ-series Functional Block Diagram QRC Control Burst Mode Operation SenseFET OLP Current Mode Control AOCP TSD OVP Auto Restart Mode Latch Mode
Normal Quasi-Resonant Switching • Advantages • Reduced switching noise (Low EMI) • Improved efficiency • Removed RCD snubber
Normal Quasi-Resonant Switching • Limitations • Intermittent switching at light load due to a relatively large LEB time • Increased switching loss at light load
Extended Quasi-Resonant Switching • Advantages • Guarantee stable operation over wide load range • Improve efficiency at light load condition
Internal Soft-start 85V input 265V input • Internal soft start (20ms) • For a fast output build up, offset is introduced in the soft start
Over load Protection - Output short 85V input 265V input
Abnormal over current protection – Diode short 85V input 265V input
Over voltage protection -Feedback open 85V input 265V input
Burst operation - basic features • Drop output voltage to below half (any level) to minimize the loss caused by leakage current in the high voltage output • Reduce the effective switching frequency to minimize switching loss • Reduce the FPS operating current in the burst operation
Burst operation - Output drop circuit • Normal mode : Vo1 (B+) is regulated • Standby mode : Vo2 is regulated
Burst operation waveforms Normal Standby Standby Normal
Burst operation waveforms Vi=85Vac Vi=265Vac 1. Vds 2. Vcc 3. Vfb 4. Id