7-Feb-2006
EP-91 12 V, 1 A, Universal Input Supply
7.5 Transformer Construction
Bobbin Set Up
Orientation
Set up the bobbin with its pins oriented to the left hand side.
Margin Tape
Apply 2.0 mm margin at the pin side of bobbin using item [6]. Match
combined height of shield, primary, and bias windings.
Start at Pin 1. Wind 14 bifilar turns of item [3] from left to right. Wind with
tight tension across entire bobbin evenly. Cut the ends of the bifilar and
leave floating.
WD1
Cancellation Winding
Insulation
1 Layer of tape [7] for insulation.
WD#2
Primary winding
Start at pin 3. Wind 28 turns of item [3] from left to right. Apply 1 Layer of
tape [7] for insulation. Wind another 28 turns from right to left. Wind with
tight tension across entire bobbin evenly. Finish at Pin 1.
1 Layer of tape [7] for insulation.
Insulation
WD #3
Bias Winding
Start at Pin 4, wind 6 trifilar turns of item [5]. Wind from left to right with
tight tension. Wind uniformly, in a single layer across entire width of
bobbin. Finish on Pin 2.
Insulation
1 Layer of tape [7] for insulation.
WD #4
Bias Winding
Start at Pin 2, wind 6 trifilar turns of item [5] from left to right with tight
tension. Wind uniformly, in a single layer across entire width of bobbin.
Finish on Pin 5.
Insulation
1 Layer of tape [8] for insulation.
Margin Tape
Apply 2.0 mm margin at the pin side of bobbin using item [6]. Match
combined height of secondary windings.
WD #5
Secondary Winding
Start at Pin 8, wind 7 turns of item [5] from left to right. Wind uniformly, in
a single layer across entire bobbin evenly. Finish on Pin 6.
3 Layers of tape [8] for insulation.
Assemble and secure core halves using item [1] and item [9]
Dip varnish using item [10] (do not vacuum impregnate)
Outer Insulation
Core Assembly
Varnish
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 15 of 36
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