AN-6982

APPLICATION NOTE

© 2010 Fairchild Semiconductor Corporation

www.fairchildsemi.com

Rev. 1.0.0 • 6/8/10

6

Design Considerations

In this section, a design procedure is presented using the

schematic in Figure 13 as reference. A 350W PFC power

supply application with universal input range is selected as a

design example. The design specifications are summarized in

Table 1.

Table 1. Design Specifications

Brownout Protection Line Voltage

Line Voltage Range

AC Input Voltage Frequency

Nominal PFC output voltage

Minimum PFC Output Voltage During Holdup Time

310V

Hold-up Time

Rated Output Power

Efficiency

η = 0.94

Switching Frequency

PFC Inductor Ripple Current

Full Load

PFC Output Voltage Ripple

IEA

RT/CT

RDY

EN

VRMS

ISENSE

IAC

SGND

OPFC

PGND

VDD

VREF

FBPFC

VEA

FAN6982

Range Enabled/Disabled

AC Input

Downstream

DC/DC Converter

PWM Controller

From Standby Auxiliary Power Supply

Figure 13. Reference Circuit for Design Example