Typical Application Circuit (Continued)
Usually, LLC resonant converters require large leakage inductance value. To obtain a large leakage inductance,
sectional winding method is used.
Core: EER3542 (Ae=107 mm2)
Bobbin: EER3542 (Horizontal)
Figure 30. Transformer Construction
Pin (S → F)
Wire
Turns
Winding Method
Section winding
Section winding
Section winding
Np
8 → 1
0.12φ×30 (Litz wire)
0.1φ×100 (Litz wire)
0.1φ×100 (Litz wire)
36
4
Ns1
Ns2
12 → 9
16 → 13
4
Pin
Specification
630μH ± 5%
135μH ± 5%.
Remark
Primary-side Inductance (Lp)
1－8
100kHz, 1V
Primary-side Effective Leakage (Lr)
1－8
Short one of the secondary windings
© 2007 Fairchild Semiconductor Corporation
FSFR series • 1.0.3
www.fairchildsemi.com
15
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