AN-6206

APPLICATION NOTE

© 2010 Fairchild Semiconductor Corporation

www.fairchildsemi.com

Rev. 1.0.0 • 4/27/10

8

Figure 14 and Figure 16 show the example design

waveform. Figure 14 shows the typical SR driving signals

and SR control signal SP-SN under CCM operation. Figure

16 shows that the freewheeling SR is turned off by the LPC

mechanism under DCM operation.

Figure 14. SR Gate is Driven by Primary-Side Control

Signal Under CCM Operatio

n

Figure 15. SIN Signal (Rising Edge) and SR

Control Signal

300W PC Power with Schottky Diodes (FYP2006DN)

Load

Input

Watts(W)

Output

Watts(W)

Efficiency

100%

357.98

305.42

85.31%

50%

174.21

152.56

87.57%

20%

70.84

70.84

85.95%

Figure 15 and Figure 17 shows the SIN signal of FAN6210

and SR control signals of FAN6206 together. The efficiency

test results are shown in Table 3 and Table 4. The

significant difference between the SR MOSFET and the

Schottky diode is shown in Table 4.

Figure 16. Freewheeling SR is Turned Off by LPC

Mechanism Under DCM Operation

Figure 17.SIN Signal (Falling Edge) and SR

Control Signal

300W PC Power with SRs (FDP5800)

Load

Input

Watts

(W)

Output

Watts

(W)

Efficiency

Vs.

Schottky

Diode

100%

347.02

305.43

88.01%

+2.70%

50%

169.75

152.69

89.94%

+2.40%

20%

69.24

61.04

88.15%

+2.20%