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 Converter (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), Abnormal

Over-Current Protection (AOCP), 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