EP-86 – 6.6 W, 3.3 V, 2 A PoE Powered Device

13-Apr-2006

Page 2 of 28

Power Integrations

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Table Of Contents

1

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

2

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

3

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

4

Circuit Operation.........................................................................................................6

4.1

General ................................................................................................................6

4.2

DPA-Switch

Primary.............................................................................................6

4.3

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

4.4

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

4.5

PoE Interface Circuit Description..........................................................................7

4.6

Wide Hysteresis Under-Voltage Lockout..............................................................8

5

Bill of Materials .........................................................................................................10

6

Layout.......................................................................................................................12

7

Transformer Design Spreadsheet.............................................................................13

8

Transformer Specification.........................................................................................15

8.1

Transformer Winding..........................................................................................15

8.2

Electrical Specifications......................................................................................15

8.3

Materials.............................................................................................................15

8.4

Transformer Build Diagram ................................................................................16

8.5

Transformer Construction...................................................................................16

9

Performance Data ....................................................................................................17

9.1

Efficiency............................................................................................................17

9.2

Load Regulation .................................................................................................18

9.3

Line Regulation ..................................................................................................18

9.4

Overload Output Current ....................................................................................19

10

Waveforms............................................................................................................20

10.1 Drain Voltage and Current, Full-Load Operation ................................................20

10.2 Output Voltage Start-Up Profile..........................................................................20

10.3 Load Transient Response (75% to 100% Load Step) ........................................21

10.4 Output Ripple Measurements.............................................................................22

10.4.1

Ripple Measurement Technique ................................................................22

10.4.2

Output Ripple Measurements.....................................................................23

11

Revision History ....................................................................................................24

Important Note:

Although this board was designed to satisfy safety isolation requirements, it has not been

agency approved. Therefore, please take the appropriate safety precautions.