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manufacturability. Power Integrations does not assume any liability arising from the use of any device or circuit

described herein. POWER INTEGRATIONS MAKES NO WARRANTY 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 (transformer construction and circuits external to the products) 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

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Rev. A 09/06

Power Integrations

5245 Hellyer Avenue

San Jose, CA 95138

Phone: 1-408-414-9200

Apps: 1-408-414-9660

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Table 1. Transformer Design Parameters.

TIW = Triple Insulated Wire, NC = No Connect, FL = Flying Lead

with load, scaling switching losses and maximizing efficiency.

The use of LinkSwitch-TN further improves efficiency due to

its 66 kHz switching frequency.

Key Design Points

• The input stage (to the left of C9) can be omitted in

applications that have a high-voltage DC bus. Capacitor

C9 is still required to provide local decoupling.

• Long cores (EEL) are ideal for this application to provide

greater bobbin width to accommodate the increased

margins required to meet safety spacings at the high

operating voltage.

• Zener diodes VR1-3 can be replaced with a single

P6KE540 device.

• The value of capacitors C5 to C8 can be reduced to 10 µF

if operation down to 57 VAC is not required (100 VAC

minimum).

• Use 0.5 W resistors for R13-16 and R6-8 to provide

adequate voltage rating.

• Efficiency falls at high line due to switching losses.

Reducing transformer capacitance by adding layers of

tape between the primary winding layers minimizes this.

TRANSFORMER PARAMETERS

Core Material

EEL16, gap for A

2

Bobbin

6+4 pin (Ying Chin YC-1604-1)

with 3 mm + 3 mm tape margins

Winding Details

Shield: 23T, 2

× 36 AWG

Primary: 184T, 36 AWG

Shield: 12T, 2

×29 AWG

Secondary: 30T, 29 AWG TIW

Winding Order

(pin numbers)

Shield (5-NC), tape, primary

(7-5), tape between layers,

shield (9-10), tape, 12 V / (4-1),

tape

Inductance

Primary: 3.5 mH ±10%

Leakage: 160

µH (max)

Primary Resonant

Frequency

500 kHz (min)

Figure 3. Full Load Efficiency vs. Input Voltage.

Figure 2. Conducted EMI (230 VAC, EN55022B Limits,

AV and QP Results).

1.0

EN55022B Limits

0.15

10.0

100.0

-20

-10

0

10

20

30

40

50

60

80

70

MHz

QP

AV

QP

AV

50

150

250

450

350

550

AC Input Voltage (V)

80

75

70

65

60

55

50

45

40