
2008 Fairchild Semiconductor Corporation
www.fairchildsemi.com
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S
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565RS
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Green-Mo
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F
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P
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Switch
(FPS)
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asi-Resonant
Operation
FSQ0565RS/RQ Rev. 1.0.3
December 2009
FSQ0565RS/RQ
Green-Mode Fairchild Power Switch (FPS) for
Quasi-Resonant Operation - Low EMI and High Efficiency
Features
!
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 (650V)
!
Built-in Soft-Start (17.5ms)
Applications
!
Power Supply for LCD TV and Monitor, VCR, SVR,
STB, and DVD & DVD Recorder
!
Adapter
Related Resources
Visit: http://www.fairchildsemi.com/apnotes/ for:
!
AN-4134: Design Guidelines for Offline Forward
Converters Using Fairchild Power Switch (FPS)
!
AN-4137: Design Guidelines for Offline Flyback
Converters Using Fairchild Power Switch (FPS)
!
AN-4140: Transformer Design Consideration for
Offline Flyback Converters Using Fairchild Power
Switch (FPS)
!
AN-4141: Troubleshooting and Design Tips for
Fairchild Power Switch (FPS) Flyback Applications
!
AN-4145: Electromagnetic Compatibility for Power
Converters
!
AN-4147: Design Guidelines for RCD Snubber of
Flyback Converters
!
AN-4148: Audible Noise Reduction Techniques for
Fairchild Power Switch (FPS) Applications
!
AN-4150: Design Guidelines for Flyback Converters
Using FSQ-Series Fairchild Power Switch (FPS)
Description
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.