Fairchild Semiconductor AN-6083 FAN6791 Application Note

About this manual

The document describes the FAN6791, a highly integrated dual-PWM combination controller designed for power supplies that include a flyback converter for standby power and a forward converter for main power. Key features include a proprietary green-mode function for offtime modulation to minimize standby power consumption, an internal high-voltage startup circuitry, and built-in synchronized slope compensation for stable peak-current-mode control.

What's inside

• Introduction
• Startup Circuitry
• Under-Voltage Lockout
• Oscillator and Green Mode
• Line Voltage Detection
• Remote On/Off
• Interleave Switching
• Built-In Slope Compensation
• Constant Power Control
• Leading Edge Blanking

Specifications

Frequently asked questions

What is the function of the green mode in the FAN6791?

The green mode function provides offtime modulation to linearly decrease the switching frequency at light-load conditions to minimize standby power consumption.

How does the FAN6791 achieve stable peak-current-mode control?

It achieves stability through built-in synchronized slope compensation which introduces a positive-going ramp in every switching cycle.