Dual Output Off-Line Non-isolated Fly-back Power Solution
AP3917B 12V/20mA+3.8V20mA EV3 Board User
’s Guide
AP3917B EV3 Page 5 of 17 06-21-2019
Rev 1.0 www.diodes.com
3.3 Transformer Specification
3.3.1 Electrical Diagram
Bobbin: EE8.3, 3+3Pin, Horizontal
Core: PC40, Ae=7mm
2
Fig. 3-2, transformer electrical diagram
3.3.2 Transformer Instructions
Winding
Wire
Turns
Notes
5-6
0.11mm*1 UEW
123
three layer with tight tension
Tape
W=5mm
2
Full layer
3-4
0.17mm*2 UEW
10.5
One layer with tight tension
Tape
W=5mm
2
Full layer
1-3
0.17mm*1 UEW
23
One layer with tight tension
Tape
W=7mm
2
Full layer
Note: the transformer need be varnished. Put the transformer in the varnish for 30min, then remove it to the oven at 90
℃
for at
least 6 hours.
3.3.3 Electrical Specifications
Item
Pins
Inductance
Conditions
Main inductance
5-6
800uH±7%
1/3/4pin open, 1V/10kHz
Leak inductance
5-6
<50uH
1/3/4pin short, 1V/10kHz
Chapter4 Evaluation Board Connections
4.1 PCB Layout
6
4
5
3
WD1,
123Ts 0.11mm*1
WD2, 10.5Ts
0.17mm*2
1
WD3, 22Ts
0.17mm*1