Power Integrations reserves the right to make changes to its products at any time to improve reliability or

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

complete list of Power Integrations' patents may be found at

www.powerint.com. Power Integrations grants its

customers a license under certain patent rights as set forth at http://www.powerint.com/ip.htm.

The PI logo,

TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, PeakSwitch, EcoSmart,

Clampless, E-Shield, Filterfuse, StackFET, PI Expert and PI FACTS are trademarks of Power

Integrations, Inc. Other trademarks are property of their respective companies. ©Copyright 2006, Power Integrations, Inc.

For the latest updates, visit

www.powerint.com

Rev. A 09/06

Power Integrations

5245 Hellyer Avenue

San Jose, CA 95138

Phone: 1-408-414-9200

Apps: 1-408-414-9660

Apps Fax: 1-408-414-9760

For a complete listing of worldwide

sales offices, please visit

www.powerint.com

Table 2. Transformer Construction Information.

TIW = Triple Insulated Wire, NC = No Connect

• Maximize the value of R8 and minimize the value of C4

for the lowest no-load consumption. However, verify

that the peak drain voltage is <650 V at high line, under

maximum overload conditions.

• Select transformer wire gauge sizes so that each winding

layer occupies the full bobbin width. This lowers leakage

inductance and improves output cross regulation.

• Use option to add E-Shield windings in PI Transformer

Designer

software to reduce conducted EMI noise

generation.

• To lower the no-load power consumption even further,

use an optional bias supply circuit to feed the rated data

sheet current (through a series resistor) to the

BP/M pin of U1.

TRANSFORMER PARAMETERS

Core Material

EF20 TDK PC40, or equivalent

A

2

Bobbin

EF20, 10 pin (5+5), horizontal

Pin Shine P-2015 or equivalent

Winding Details

Shield: 15T, 2

× 31 AWG

Primary: 36T + 35T, 33 AWG

Shield: 4T, 5

× 29 AWG

5 V: 3T, 4

× 26 AWG T.I.W.

24 V: 11T, 26 AWG T.I.W.

(4

×26 AWG = quadfilar 26

AWG)

Winding Order

(Pin Numbers)

Apply 2 mm tape margin to both

sides of bobbin

Shield (1-NC), tape, Primary

(3-1), Shield (NC-1), 5 V (6-8),

24 V (10-6)

Inductance

Primary: 1.62 mH

±5%

Leakage: 50

µH maximum

Primary Reso-

nant Frequency

800 kHz (minimum)

Figure 3. Worst Case Conducted EMI at 230 VAC, Full Load

Output Return Grounded.

Figure 2. Full Load Efficiency vs Input Voltage.

185

205

225

245

265

AC Input Voltage (V)

80

79

78

77

76

75

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

Table 1. Worst Case Output Cross Regulation at 185 VAC

Output Loads Varied as Shown and Maximum

Deviation Recorded.

Output

(V)

Load

Range

(mA)

Regulation (%)

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

5

50-250

24

88-350