DER-41

5V and 22V LCD TV Standby PS

November 18, 2004

Table Of Contents

1

Introduction .................................................................................................................3

2

Photograph .................................................................................................................3

3

Power Supply Specification ........................................................................................4

4

Schematic ...................................................................................................................5

5

Circuit Description.......................................................................................................6

5.1

Input Rectification ................................................................................................6

5.2

Auxiliary Bias Supply and the 22V Primary Output ..............................................6

5.3

Primary DRAIN Voltage Clamp Circuit.................................................................6

5.4

Output Rectification and Filtering.........................................................................6

5.5

Output Voltage Sensing and Feedback ...............................................................6

6

PCB Layout.................................................................................................................7

7

Bill Of Materials...........................................................................................................8

8

Transformer Specification ...........................................................................................9

8.1

Electrical Diagram................................................................................................9

8.2

Electrical Specifications .......................................................................................9

8.3

Materials ..............................................................................................................9

8.4

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

8.5

Transformer Construction ..................................................................................10

9

Transformer Spreadsheets .......................................................................................11

10

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

10.1 Line and Load Regulation..................................................................................14

10.2 Efficiency ...........................................................................................................14

10.3 No-Load and Minimum Load Input Power .........................................................15

10.4 Overload Protection ...........................................................................................15

11

Thermal Performance............................................................................................16

12

Waveforms ............................................................................................................17

12.1 Drain Voltage Normal Operation........................................................................17

12.2 Output Voltage Start-up Profile..........................................................................17

12.3 Drain Voltage Start-up Profile ............................................................................17

12.4 Output Ripple Measurements ............................................................................18

12.4.1

Ripple Measurement Technique.................................................................18

12.4.2

Measurement Results.................................................................................19

13

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

14

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

Important Note:

Although this board is designed to satisfy safety isolation requirements, the engineering

prototype has not been agency approved. Therefore, all testing should be performed

using an isolation transformer to provide the AC input to the prototype board.

Design Reports contain a power supply design specification, schematic, bill of materials,

and transformer documentation. Performance data and typical operation characteristics

are included. Typically only a single prototype has been built.

Page 2 of 22

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