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.

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