www.powerint.com

A

9/02

DI-27

For the latest updates, visit our Web site: www.powerint.com

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, nor does it convey any

license under its patent rights or the rights of others. The products and applications illustrated herein 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.

The PI Logo, TOPSwitch, TinySwitch and EcoSmart are registered trademarks of Power Integrations, Inc.

PI Expert is a trademark of Power Integrations, Inc. ©Copyright 2002, Power Integrations, Inc.

WORLD HEADQUARTERS

AMERICAS

Power Integrations, Inc.

San Jose, CA 95138 USA

Customer Service:

Phone:

+1 408-414-9665

Fax:

+1 408-414-9765

e-mail: usasales@powerint.com

CHINA

Power Integrations International

Holdings, Inc.

China

Phone:

+86-755-8367-5143

Fax:

+86-755-8377-9610

e-mail: chinasales@powerint.com

SINGAPORE

Power Integrations, Singapore

Republic of Singapore 308900

Phone:

+65-6358-2160

Fax:

+65-6358-2015

e-mail: singaporesales@powerint.com

JAPAN

Power Integrations, K.K.

Keihin-Tatemono 1st Bldg.

Japan

Phone:

+81-45-471-1021

Fax:

+81-45-471-3717

e-mail: japansales@powerint.com

EUROPE & AFRICA

Power Integrations (Europe) Ltd.

United Kingdom

Phone:

+44-1344-462-300

Fax:

+44-1344-311-732

e-mail: eurosales@powerint.com

KOREA

Power Integrations

International Holdings, Inc.

Seoul, Korea

Phone:

+82-2-782-2840

Fax:

+82-2-782-4427

e-mail: koreasales@powerint.com

TAIWAN

Power Integrations

International Holdings, Inc.

Taipei, Taiwan

Phone:

+886-2-2727-1221

Fax:

+886-2-2727-1223

e-mail: taiwansales@powerint.com

INDIA (Technical Support)

Innovatech

Bangalore, India

Phone:

+91-80-226-6023

Fax:

+91-80-228-9727

e-mail: indiasales@powerint.com

APPLICATIONS HOTLINE

APPLICATIONS FAX

World Wide +1-408-414-9660

World Wide +1-408-414-9760

Core Material

Bobbin

Winding Order

(pin numbers)

Primary Inductance

Primary Resonant

Frequency

Leakage Inductance

TRANSFORMER PARAMETERS

Table 1. Transformer Construction Information.

Figure 2. No-load Input Power vs. BYPASS Pin Current.

EE16

Nippon Ceramic NC-2H

A

2

EE16 10 pin

(Ying Chin YC1607 or equivalent)

Primary (1-2), Tape

12 V (10-9), Tape

Bias (3-4), Tape

3.67 mH ±10%

500 kHz (minimum)

300 µH (maximum)

Key Design Points

• Design bias winding circuit to provide 250

µA to 300 µA

at no-load.

• Ensure C5 is large enough to supply above current at the

very low no-load switching frequencies.

•Minimize secondary circuit bias currents. Use low current

feedback Zeners for best tolerance.

• Zener or RCD clamp can be used to slightly reduce no-load

consumption further. Use a 200 V Zener or maximize

resistor value in RCD clamp for lowest losses.

• Design transformer with low reflected voltage to minimize

clamp losses.

•Wind transformer for lowest leakage inductance. Choose

wire gauges to completely fill winding layers.

•Wind transformer with tape between primary layers to

further reduce intra-winding capacitance.

100

1

0

300

400

100

200

500

BYPASS Pin Current (µA)

10

10

0

2

80

200

240

120

160

AC Line Voltage (A)

4

6

8

Zener Clamp

RC Clamp

Figure 3. No-load Input Power Variation with Input Voltage.