FSQ0365_11 Datasheet, PDF (1/21 Pages) Fairchild Semiconductor – Green Mode Fairchild Power Switch for Valley Switching Converter – Low EMI and High Efficiency

August 2011
FSQ0365, FSQ0265, FSQ0165, FSQ321
Green Mode Fairchild Power Switch (FPS™)
for Valley Switching Converter – Low EMI and High Efficiency
Features
 Optimized for Valley Switching Converter (VSC)
 Low EMI through Variable Frequency Control and
Inherent Frequency Modulation
 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
 Pulse-by-Pulse Current Limit
 Protection Functions: Overload Protection (OLP),
Over-Voltage Protection (OVP), Abnormal Over-
Current Protection (AOCP), Internal Thermal
Shutdown (TSD)
 Under-Voltage Lockout (UVLO) with Hysteresis
 Internal Startup Circuit
 Internal High-Voltage SenseFET: 650V
 Built-in Soft-Start: 15ms
Applications
 Power Supplies for DVP Player, DVD Recorder,
Set-Top Box
 Adapter
 Auxiliary Power Supply for PC, LCD TV, and PDP TV
Description
A Valley Switching Converter 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 valley switching
operation 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 discrete MOSFET and PWM controller
solutions, the FSQ-series reduces 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 valley switching fly-back converters.
Related Application Notes
 AN-4137 - Design Guidelines for Offline Flyback
Converters Using Fairchild Power Switch (FPS™)
 AN-4141 - Troubleshooting and Design Tips for
Fairchild Power Switch (FPS™) Flyback
Applications
 AN-4147 - Design Guidelines for RCD Snubber of
Flyback Converters
 AN-4150 - Design Guidelines for Flyback
Converters Using FSQ-series Fairchild Power
Switch (FPS™)
 AN-4134 - Design Guidelines for Off-line Forward
Converters Using Fairchild Power Switch (FPS™)
© 2007 Fairchild Semiconductor Corporation
FSQ0365, FSQ0265, FSQ0165, FSQ321 • Rev. 1.0.6
www.fairchildsemi.com