DER-94
LCD Monitor Internal Supply
September 12, 2005
7.5 Transformer Construction
Winder
Direction
Core
Using two 35 mm long pieces of item [5] for each core,
Preparati wrap both core halves (item [1]) as shown in Figure 1.
on
Primary Using item [7], apply a 3 mm wide margin on each side of
Margins the bobbin winding area. Match margin height to primary
and bias windings.
½
Start at Pin 5. Wind 25 turns of item [3] in 1 layer. Finish Forward
Primary - on Pin 1. Sleeve start and finish leads (item [8]).
Basic
Insulation
Bifilar
Use one layer of item [6] for basic insulation.
Starting at pin 2, wind 7 bifilar turns of item [3]. Spread Forward
turns evenly across bobbin. Finish at pin 3. Sleeve start
Bias
winding and finish leads (item [8]).
Reinforce Use three layers of item [6] for reinforced insulation.
d
Insulation
Secondar Using item [7], apply a 3 mm wide margin on each side of
y Margins the bobbin winding area. Match margin height to
secondary windings.
12V
Start at Pin 10. Wind 4 bifilar turns of item [4]. Spread
Bifilar
turns evenly across bobbin. Finish on Pin 7. Sleeve start Forward
Secondar and finish leads (item [9]).
y
Winding
5V Trifilar Start at Pins 6 and 7. Forward wind 3 trifilar turns of item
Secondar [4] directly on top of 12 V winding. Spread turns evenly Forward
y
across bobbin. Finish on Pins 8 and 9. Sleeve start and
Winding finish leads (item [9]).
Primary Using item [7], apply a 3 mm wide margin on each side of
Margins the bobbin winding area. Match margin height to primary
winding.
Reinforce Use three layers of item [6] for reinforced insulation.
d
Insulation
½
Start at Pin 1. Wind 24 turns of item [3] in 1 layer. Finish Forward
Primary - on Pin 4. Sleeve start and finish leads (item [8]).
Outer
Wrap
Wrap windings with 3 layers of tape [item [5].
Assembly Assemble bobbin and core halves. Varnish impregnate
assembled transformer (item [10]).
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
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