DER-95

30 W Adapter for Portable DVD

September 12, 2005

Page 2 of 22

Power Integrations

Tel: +1 408 414 9200 Fax: +1 408 414 9201

www.powerint.com

Table Of Contents

1

Introduction................................................................................................................. 4

2

Power Supply Specification ........................................................................................ 5

3

Schematic................................................................................................................... 6

4

Circuit Description ...................................................................................................... 7

4.1

Input EMI Filtering ............................................................................................... 7

4.2

Reduced current limit .......................................................................................... 7

4.3

Output Rectification ............................................................................................. 7

4.4

Output Feedback................................................................................................. 7

5

PCB Layout ................................................................................................................ 8

6

Bill Of Materials .......................................................................................................... 9

7

Transformer.............................................................................................................. 10

7.1

Transformer Diagram ........................................................................................ 10

7.2

Electrical Specifications..................................................................................... 10

7.3

Materials............................................................................................................ 10

7.4

Detailed copper shield....................................................................................... 11

7.5

Transformer Construction.................................................................................. 11

7.6

Winding Instructions .......................................................................................... 11

8

Transformer Spreadsheets....................................................................................... 12

9

Performance Data .................................................................................................... 14

9.1

Efficiency........................................................................................................... 14

9.2

No-Load Input Power Integrations..................................................................... 14

9.3

Output regulation............................................................................................... 15

9.3.1

Line regulation............................................................................................ 15

9.3.2

Load regulation (taken at the end of the output cable) ............................... 15

9.4

Thermal Performance........................................................................................ 15

9.5

Maximum output current.................................................................................... 16

10

Waveforms............................................................................................................ 16

10.1

Drain Voltage, Normal Operation ...................................................................... 16

10.2

Output Voltage Start-up Profile ......................................................................... 16

11

Output Ripple Measurements ............................................................................... 17

11.1.1

Ripple Measurement Technique ................................................................ 17

11.1.2

Measurement Results ................................................................................ 18

12

Loop performance................................................................................................. 19

13

Conducted EMI ..................................................................................................... 20

14

Revision History .................................................................................................... 21

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.