DER-19

TOP245P Multiple Output Set Top Box

March 30, 2004

Page 2 of 25

Power Integrations, Inc.

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

TOPSwitch Primary............................................................................................. 7

4.3

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

4.4

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

5

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

6

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

7

Transformer Specification ........................................................................................ 10

7.1

Electrical Diagram............................................................................................. 10

7.2

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

7.3

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

7.4

Transformer Build Diagram ............................................................................... 11

7.5

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

8

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

9

Performance Data .................................................................................................... 15

9.1

Efficiency........................................................................................................... 15

9.2

No-load Input Power ......................................................................................... 16

9.3

Peak Power....................................................................................................... 16

9.4

Regulation......................................................................................................... 16

9.4.1

Load........................................................................................................... 16

9.4.2

Line ............................................................................................................ 17

9.5

Cross Regulation .............................................................................................. 17

10

Thermal Performance........................................................................................... 18

11

Waveforms ........................................................................................................... 18

11.1

Drain Voltage and Current, Normal Operation .................................................. 18

11.2

Output Voltage Start-up Profile (Full Power) ..................................................... 19

11.3

Drain Voltage and Current Start-up Profile ....................................................... 20

11.4

Load Transient Response ................................................................................. 20

11.5

Output Ripple Measurements ........................................................................... 21

11.5.1

Ripple Measurement Technique ................................................................ 21

11.5.2

Measurement Results ................................................................................ 22

12

Conducted EMI..................................................................................................... 24

13

Revision History.................................................................................................... 25