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C

12/04

DI-23

Power Integrations

5245 Hellyer Avenue

San Jose, California 95138

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The PI logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch and EcoSmart are registered trademarks of Power Integrations. PI Expert and

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are trademarks of Power Integrations. Copyright 2004, Power Integrations

Power Integrations may make changes to its products at any time. Power Integrations has no liability arising from your use of any information, device or circuit described

herein nor does it convey any license under its patent rights or the rights of others. POWER INTEGRATIONS MAKES NO WARRANTIES HEREIN AND SPECIFICALLY

DISCLAIMS ALL WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,

AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS. The products and applications illustrated herein (including circuits external to the products and transformer

construction) may be covered by one or more U.S. and foreign patents or potentially by pending U.S. and foreign patent applications assigned to Power Integrations.

A complete list of Power Integrations' patents may be found at www.powerint.com.

For the latest updates, visit www.powerint.com

Key Design Points

• Use K

0.4–0.6 for better efficiency.

• Select V

optimum performance.

• Opto with CTR range of 80% to 160% recommended.

• PCB traces which carry high switching voltages and current

should be short and wide to reduce EMI.

Table 1. Transformer Construction Information.

Table 2. Worst Case Output Cross-Regulation - Outputs Taken

from Minimum to Maximum Load.

Figure 2. Conducted Emissions – EN55022 Class B (QP and AV),

230 VAC, Full Load, Artificial Hand Connected to

Secondary Return.

1.0

0.15

10.0

130.0

-20

-10

0

10

20

30

40

50

60

80

70

MHz

AV

QP

Average

Quasi Peak

• Reduce leakage inductance and improve cross-regulation

by filling each winding layer across the entire width of the

bobbin.

• Use shield windings to improve EMI.

• Use a layer of insulation tape between layers of primary

winding to reduce inter-winding capacitance.

• D5 should be a GP type (glass passivated) to ensure a

controlled reverse recovery time.

Load

Range

(Amp)

3.3

0.3-1.5

5

0.3-0.9

30

0.01-0.03

Regulation (%)

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

TRANSFORMER PARAMETERS

Core Material

EE25, Nippon Ceramic NC-2H or

2

Bobbin

YW-360-02B, YIH-HWA, 10 pin Vertical

Primary Resonant

Frequency

500 kHz (minimum)

Winding Order

(Pin Numbers)

Shield (1-NC), 3 x tape, Primary (2-1),

with tape between layers, tape,

Bias (5-4), 6 x tape, 3.3 V (6-7),

tape, 5 V (9-6), tape, 30 V (10-9),

2 x tape, Shield (1-3), 3 x tape

Winding Details

Shield: 15T, 2 x 29 AWG

Primary: 49T, 27 AWG

Bias: 7T, 3 x 28 AWG

3.3 V: 2T, 3 x 26 AWG T.I.W.

5 V: 1T, 26 AWG T.I.W.

30 V: 13T, 26 AWG T.I.W.

(T.I.W. = Triple Insulated Wire)

Inductance

Primary: 1 mH ±10%,

Leakge: 30 µH (maximum)