Introduction
This application note describes a detailed design strategy for a high-efficiency, compact flyback converter. Design considerations and mathematical equations are presented as well as guidelines for a printed circuit board layout. The highly integrated FAN6751 series of PWM controllers provides several features to enhance the performance for LCDM/TV, NB, and adapters.

FEATUREs
■ High-Voltage Startup
■ Low Operating Current: 4mA
■ Linearly Decreasing PWM Frequency to 18KHz
■ Fixed PWM Frequency: 65KHz
■ Peak-Current-Mode Control
■ Cycle-by-Cycle Current Limiting
■ Leading-Edge Blanking (LEB)
■ Synchronized Slope Compensation
■ Internal Open-loop Protection
■ GATE Output Maximum Voltage Clamp: 18V
■ VDD Under-Voltage Lockout (UVLO)
■ VDD Over-Voltage Protection (OVP)
■ Internal Recovery Circuit (OVP, OLP)
■ Internal Sense Short-Circuit Protection
■ External Constant Power Limit (Full AC Input Range)
■ Internal OTP Sensor with Hysteresis
■ Built-in 5ms Soft-Start Function
■ Built-in VIN Pin Pull HIGH (> 4.7V) Recovery Function for Second-Side Output OVP
■ Brownout Protection with Hysteresis

APPLICATIONs
General-purpose, switch-mode power supplies and flyback power converters, including:
■ Power Adapters
■ Open-frame SMPS
■ LCD Monitor/TV