AND8039 Datasheet, PDF (7/12 Pages) ON Semiconductor – The One-Transistor Forward Converter

+V_IN
GND
AND8039/D
TP5
R13 C12
10
10 T1
R1 R2
+
C1
Z1 ^{D1 +}
C2
RESET
WINDING
9
V_aux
8
Z2
D5
TP2
V_CC
1, 2
4, 5
6
R12 D4
7
REF ₈
7
C3
U1
R3
UC3845 ₃
OSC
4
C4
1
25
COMP
C5 V_FB
Q2
R9
C8
TP3
TP4
C7
R8 R8A
C6 R4
L1
L2
+
+
D3
C9
C10
V_aux
TP6
R10
TP7
R11
+V_OUT
+
C11
GND
R5
TP1
Figure 5. 112 Watt, One–Transisitor Forward Converter
Conclusion
This application note illustrated the design steps needed
to complete a one–transistor forward converter. This
demonstration unit is only for instruction and to complete a
design for the “real world” one should also include:
dielectric isolation from the input to output, an input
rectification and filter section and some additional methods
of protection.
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