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9/02

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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.

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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

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Power Integrations, Singapore

Republic of Singapore 308900

Phone:

+65-6358-2160

Fax:

+65-6358-2015

e-mail: singaporesales@powerint.com

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Power Integrations, K.K.

Keihin-Tatemono 1st Bldg.

Japan

Phone:

+81-45-471-1021

Fax:

+81-45-471-3717

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Power Integrations (Europe) Ltd.

United Kingdom

Phone:

+44-1344-462-300

Fax:

+44-1344-311-732

e-mail: eurosales@powerint.com

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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

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+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

Key Design Points

• Use low cost optocoupler - CTR is unimportant for output

regulation.

• PCB traces that carry switching currents should be short

and wide to minimize EMI.

• Select input and output capacitors to meet ripple current

requirements.

• Diode D2 must be an ultra-fast type, with reverse recovery

time (t

•Minimum recommended output voltage in this topology is

5 V.

Lower voltages may cause continuous mode operation,

forcing high reverse recovery currents in D2 and therefore,

lowering efficiency.

Figure 2. Output Power vs. Input Power.

0.2

0.4

1

1.2

0.6

0.8

0

.200

.400

.600

.800

Output Power (W)

0

VIN = 115 VAC

VIN = 230 VAC

20

40

100

60

80

50

100

150

200

250

300

Input Voltage (VAC)

0

Figure 3. No-load Power Consumption.

50

80

60

70

0

20

40

60

80

100

120

Output Power (mA)

40

VIN = 115 VAC

VIN = 230 VAC

Figure 4. Efficiency vs. Output Current.