EPR-54 Datasheet, PDF (15/40 Pages) Power Integrations, Inc. – Engineering Prototype Report for EP 54 - 2.75 W Charger/Adapter Using LNK520P

07-May-2004
EPR-54 – LinkSwitch 2.75 W Low Cost Charger / Adapter
7.5 Transformer Construction
Bobbin Preparation
Shield Winding #1
Basic Insulation
Terminate
Shield Winding #1
Basic Insulation
(continued)
Primary
Winding #2
Foil Shield
Margin Tape
Bobbin Preparation
Secondary
Winding #3
Basic Insulation
Margin Tape
L and R
Bias
Winding #4
Basic Insulation
Bias
Winding #4
(continued)
Outer
Insulation
Final Assembly
Pull Pin 8-10 on bobbin [2] to provide polarization.
Set bobbin with pins 1-5 on right hand side.
Start at Pin 1. Wind 33 turns of item [3] from right to left in 1 layer across
the entire width of the bobbin.
Temporarily terminate wire on left hand side of bobbin.
Apply 1 layer of tape item [7].
Terminate item [3] on pin 3.
Cut pin 3 below termination to prevent contact with pcb trace.
Apply an additional 3 layers of tape item [7].
Start at pin 2. Wind 100 turns of item [3] in 3 layers, plus 3 to 5 additional
turns. Wind uniformly across the entire width of the bobbin with no empty
space or gaps in any layer. Finish at pin 1.
Assemble and apply foil shield [4] starting 3 mm from bottom side of
bobbin [2]; such that foil termination wire aligns with pin 4. Insert the foil
shield assembly [4] beneath a 10-15 mm long piece of tape (to hold in
place).
Wrap beneath 1 layer item [7] and terminate foil at pin 4.
Apply 4 layers of item [11] on both sides of the bobbin ensuring no space
to either bobbin wall.
Change the bobbin [2] orientation with pins 6-10 on right hand side.
Maintain same spindle rotation direction.
Temporarily start at pin 1. Wind 8 turns item [5] in 1 layer from left to
right. Wind uniformly across the entire width of the bobbin with no empty
space or gaps in the layer. Finish at pin 7.
Remove start from pin 1 and reattach to pin 6.
Apply 2 layers tape item [7].
Apply 4 layers of item [11] on left side of the bobbin ensuring no space to
bobbin wall.
Apply 4 layers of item [12] on right side of the bobbin ensuring no space
to bobbin wall.
Start at pin 4. Wind 14 turns item [6] from left to right. Wind uniformly
across the entire width of the bobbin with no empty space or gaps in the
layer.
Apply 1 layer of tape item [6], maintaining bias winding exit at edge of
margin tape barrier.
Continue winding item [6] from right to left. Wind a total of 26 turns
item [6]. Finish on pin 5.
Apply 2 layers of tape item [7].
Assemble and secure core halves with item [12].
Dip varnish and cure (do not vacuum impregnate).
Page 15 of 40
Power Integrations
Tel: [phone] Fax: [phone]
www.powerint.com