2^nd Generation Quasi-Resonant (QR-II^TM ) PWM Controller ^{with Brownout Protection}

FEATURES

◆   Easily Meet EPS Level 6

◆   AC Brownout Protection (BOP)

◆   Proprietary QR-II^TM Technology:

●Digital Anti-jitter for Audio Noise Free Operation

● Digital Frequency Foldback

● Digital Frequency Jittering for Better EMI

◆   Less than 100mW Standby Power

◆   Multi-Mode Operation for High Efficiency

◆   12.7us Maximum On Time

◆   80KHz Maximum Frequency Limit

◆   52KHz Frequency Low Clamping in QR Mode

◆   65% Maximum Duty Cycle

◆   Adaptive Slope Compensation for CCM Mode

◆   Built-in Soft Start Function

◆   Pin Floating Protection

◆   Built-in Synchronous Slope Compensation

◆   Cycle-by-Cycle Current Limiting

◆   Leading Edge Blanking (LEB)

◆   Constant Power Limiting

◆   VDD UVLO, OVP & Clamp

APPLICATIONS

Offline AC/DC Flyback Converter for

◆   AC/DC Adaptors

◆   SMPS Power Supply

GENERAL DESCRIPTION

SF5773S is a high performance, 2^nd Generation Quasi-Resonant (QR-II^TM) PWM controller for offline flyback power converter applications. The built-in proprietary QR-II^TM technology with high level protection features improves the SMPS reliability and performance.

In SF5773S, the “Digital Anti-Jitter” function can automatically select and lock a valley at a given loading, which can achieve audio noise free operation. On the other hand, the “Digital Frequency Jittering” function makes the system have superior EMI performance than conventional QR system.

SF5773S is a multi mode controller. When full loadings, the IC works in CCM mode or QR mode based on the AC line input. When the loading goes low, the IC enters into “Digital Frequency Foldback” mode to boost power conversion efficiency. When the output power is very small, the IC enters into burst mode and can achieve less than 100mW no load power.

SF5773S integrates functions and protections of Under Voltage Lockout (UVLO), VCC Over Voltage Protection (OVP), Output Over Voltage Protection (Output OVP), Cycle-by-cycle Current Limiting (OCP), Pin Floating Protection, Over Load Protection (OLP), AC Brownout Protection, Soft Start, VCC Clamping, Gate Clamping, etc. In SF5773S, the protection functions are auto-recovery mode protection.

 SF5773S is available in SOT23-6 package.