FAIRCHILD AN-6756 Application Guide for FAN6756 Controlling a Flyback Power Supply with Ultra-Low Standby Power

AN-6756 Applying FAN6756 to Control a Flyback Power Supply with Ultra-Low Standby Power

discharge methods. At no-load or extremely light-load

1. Introduction

conditions, Standby Mode dramatically reduces the switching

Requirements for low standby power consumption are losses by minimizing the switching frequency while increasing due to the environmental impact of the energy maintaining the controller supply voltage at the minimum wasted by idle electronic devices. Fairchild’s new-generation level. Combined with ultra-low operation current in Standby green-mode PWM controller, FAN6756, incorporates Mode, the power consumption of PWM controller itself is innovative m WSaver™ technology, which dramatically also minimized. reduces the standby and no-load power consumption of a

This application note presents the step-by-step design with

power supply with minimum external components.

an example of applying FAN6756 to a flyback power

The AX-CAP™ innovation, one of the m WSaver TM supply. It covers designing of the transformer and selecting technologies, removes the X-capacitor bleeder resistor and its the external components. loss in EMI filter stage through intelligent detection and

BD1 RDOCDO

CSN RSN DO

CO CP VO

1N4007 CIN

RSENSE

FAN6756

GATE 8GND

FB VDD

NC SENSE

PC817A

HV RT (secondary- RF CF

PC817A side)

(primary- CFB

side) RA

CDD KA431

Figure 1. Typical Application

© 2011 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 1/5/12