EP48 – 12 V, 1.44 W, Non-Isolated Buck Converter

02-May-2005

Table Of Contents

1

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

2

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

3

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

4

Circuit Description ......................................................................................................5

4.1

Input Stage and EMI Filtering ..............................................................................5

4.2

LinkSwitch-TN .....................................................................................................5

4.3

Output Rectification .............................................................................................6

4.4

Output Feedback.................................................................................................6

4.5

Operation Below Minimum Drain Voltage Specification ......................................7

5

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

6

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

7

Performance Data ......................................................................................................9

7.1

Efficiency .............................................................................................................9

7.2

No-load Input Power............................................................................................9

7.3

Regulation .........................................................................................................10

7.3.1

Load ...........................................................................................................10

7.3.2

Line ............................................................................................................10

8

Thermal Performance...............................................................................................11

9

Waveforms ...............................................................................................................12

9.1

Drain Voltage and Current, Normal Operation...................................................12

9.2

Drain Voltage and Current Start-up Profile ........................................................12

9.3

Output Voltage Start-up Profile..........................................................................13

9.4

Load Transient Response (75% to 100% Load Step) .......................................13

9.5

Output Ripple Measurements............................................................................14

9.5.1

Ripple Measurement Technique ................................................................14

9.5.2

Measurement Results ................................................................................15

10

Conducted EMI .....................................................................................................16

11

Revision History ....................................................................................................18

Important Note:

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

has not been agency approved. In addition, as the output is not electrically isolated from

the input, all testing should be performed using an isolation transformer to provide the AC

line input to the prototype board.

Page 2 of 20

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