DER-99 Datasheet, PDF (14/29 Pages) Power Integrations, Inc. – 17.4 W Power Supply using TOP244P

DER-99
Set Top Box 17.4 W Power Supply
September 12, 2005
7.5 Transformer Construction
Bobbin Orientation
Safety Margin
Bias Winding
Tape
Primary
Basic Insulation
Balance Winding
Insulation
Safety Margin
9V, 5V and 3V3
Winding
Insulation
Final Assembly
Place bobbin, item [2] with the pin side oriented to the left hand side
Wind margin tape, item [7] on the pin side of the bobbin. Also wind margin
tape, item [8] on the top side of the bobbin. Match the height of the tape
with the height of the primary side windings.
Start at Pin3. Wind 9 turns of item [3] from left to right. Bring the wire lead
out and connect it to pin 4. Then bring the wire lead back to the winding
area to continue winding 9 more turns from left to right on the same layer.
The layer should be uniformly covering the whole winding area. Cut the
finish lead at the end of the winding.
1 layer of item [9] for basic insulation.
Start at pin 2, wind 20 turns of item [4] from left to right. Distribute the 20
turns uniformly scattered on the whole winding area. Add two layers of
tape, item [9]. Wind 40 more turns on a second layer from right to left.
Wind tightly and uniformly across whole layer. Finish on pin 1
1 layer of item [9] for basic insulation.
Start on pin 1 using item [6] as shown in figure 7. Start at pin 1. Wind 2
turns in reverse winding direction. Finish lead is not connected.
Use 3 layers of item [10] for basic insulation
Wind margin tape, item [7] on the pin side of the bobbin. Also wind margin
tape, item [8] on the top side of the bobbin. Match the height of the tape
with the height of the secondary side windings.
Wind secondary winding in Normal winding direction. The three
windings should be wound in a single layer scattered along the winding
area.
9V Winding. Two trifilar turns of item [5] from left to right. Start at pin 8,
finish at pin 7
5V Winding. One trifilar turn of item [5] from left to right. Start at pin 7,
finish at pin 5
3.3 V Winding. Two trifilar turns of item [5] from left to right. Start at pin 5,
finish at pin 6
Apply 3 layer item [10]
Assemble and secure core halves [1] with bobbin [2] Varnish impregnate
item [11]
Page 14 of 29
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