HV-mW^TM、2^nd Generation Quasi-Resonant (QR-II^TM ) PWM Controller

With PFC ON/OFF Control

FEATURES

◆   Meet EPS Level 6

◆   Smart PFC Control Function Integrated

◆   Proprietary QR-II^TM Technology:

●Digital Anti-jitter for Audio Noise Free Operation

● Digital Frequency Foldback

● Digital Frequency Jittering

◆   Proprietary HV-mW^TM to Achieve Ultra Low Standby Power

◆   Multi-Mode Operation for High Efficiency

◆   12.7us Maximum On Time

◆   80KHz Maximum Frequency Limit

◆   53KHz Frequency Low Clamping in QR Mode

◆   Maximum 65% Duty Cycle

◆   Adaptive Slope Compensation for CCM Mode

◆   Latch Plug-off Protection

◆   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

SF5897 is a high performance, 2^nd Generation Quasi-Resonant (QR-II^TM) PWM controller for offline flyback power converter applications. The built-in proprietary HV-mW^TM technology and QR-II^TM technology with high level protection features can improve the SMPS reliability and performance. SF5897 can turn off FPC power supply for higher efficiency at light load.

In SF5897, 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.

SF5897 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 ultra low standby power.

SF5897 integrates functions and protections of Under Voltage Lockout (UVLO), VDD Over Voltage Protection (VDD OVP), Output Over Voltage Protection (Output OVP), Cycle-by-cycle Current Limiting (OCP), Pin Floating Protection, Over Load Protection (OLP), Soft Start, VDD Clamping, Gate Clamping, etc. In SF5897, VDD OVP and Output OVP are latch mode protections, the other protections are auto-recovery mode.

SF5897 is available in SOP8 package.