Title
Specification
Application
Author
Document
Number
Date
Revision
Reference Design Report for a 30 W Supply
Using TOPSwitch
®
-JX TOP266VG
85 VAC – 264 VAC Input; 12 V, 2.5 A Output
General Purpose
Applications Engineering Department
RDR-242
March 1, 2010
1.2
Summary and Features
Highly energy efficient
Very low no-load input power: < 80 mW at 230 VAC
Full load efficiency >84% at 115 VAC / 47 Hz
Efficiency >80% above 8% load
Average efficiency >84% (25%, 50%, 75%, 100% load points)
Simplifies meeting ENERGY STAR 2.0, 80 Plus and EuP requirements
725 V MOSFET rating allowed high turns ratio (V
OR
) and use of 60 V Schottky output diode
Low cost, low component count and small PCB footprint solution
132 kHz operation optimizes core size and efficiency performance
Low-profile eDIP
™
package with no external heatsink
Integrated Protection and Reliability Features
Line undervoltage lock out (UVLO) and line overvoltage shutdown prevents output glitching
and improves reliability
Primary sensed output overvoltage shutdown (OVP) eliminates second optocoupler
Auto recovery output over current (OCP) and short circuit protection
Flat overload power with line voltage
Meets limited power source (LPS) <100 VA requirement with a single point of failure
Accurate thermal shutdown with large hysteresis
PATENT INFORMATION
The products and applications illustrated herein (including transformer construction and circuits external to the products) 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. Power Integrations grants its customers a license under
certain patent rights as set forth at <http://www.powerint.com/ip.htm>.
Power Integrations
5245 Hellyer Avenue, San Jose, CA 95138 USA.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
RDR-242 – 30 W Open Frame Supply using TOP266VG
01-Mar-10
Table of Contents
Introduction.................................................................................................................4
Power Supply Specification ........................................................................................6
Schematic...................................................................................................................7
Circuit Description ......................................................................................................8
4.1
Key Design Decisions .........................................................................................8
4.1.1
PI part selection ...........................................................................................8
4.1.2
Transformer Core Selection .........................................................................8
4.1.3
Line Sense Resistor Values .........................................................................8
4.1.4
Clamp Configuration – RZCD vs RCD .........................................................9
4.1.5
Feedback Configuration .............................................................................10
4.1.6
Output Rectifier Choice ..............................................................................10
4.2
Function Block Descriptions ..............................................................................11
4.2.1
Input EMI Filtering ......................................................................................11
4.2.2
TOPSwitch-JX Primary...............................................................................11
4.2.3
Thermal Overload Protection .....................................................................11
4.2.4
Output Overvoltage Protection ...................................................................11
4.2.5
Output Power Limiting with Line Voltage....................................................11
4.2.6
Output Feedback........................................................................................12
4.2.7
Output Inductor Post Filter Soft-Finish .......................................................12
5 PCB Layout ..............................................................................................................13
6 Bill of Materials .........................................................................................................14
7 Transformer Specification.........................................................................................16
7.1
Electrical Diagram .............................................................................................16
7.2
Electrical Specifications.....................................................................................16
7.3
Materials............................................................................................................16
7.4
Transformer Build Diagram ...............................................................................17
7.5
Transformer Construction..................................................................................18
8 Transformer Design Spreadsheet.............................................................................19
9 Performance Data ....................................................................................................24
9.1
Active Mode Efficiency ......................................................................................24
9.2
Energy Efficiency Requirements .......................................................................27
9.2.1
USA Energy Independence and Security Act 2007 ....................................27
9.2.2
ENERGY STAR EPS Version 2.0 ..............................................................28
9.3
No-load Input Power..........................................................................................29
9.4
Available Standby Output Power.......................................................................30
9.5
Regulation .........................................................................................................31
9.5.1
Load ...........................................................................................................31
9.5.2
Line ............................................................................................................32
9.6
Efficiency ...........................................................................................................33
9.6.1
Load ...........................................................................................................33
10
Power Limit ...........................................................................................................35
11
Thermal Performance ...........................................................................................36
12
Waveforms............................................................................................................37
12.1 Drain Voltage and Current, Normal Operation...................................................37
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
1
2
3
4
Page 2 of 59
01-Mar-10
RDR-242 – 30 W Open Frame Supply using TOP266VG
12.2 V
OUT
and Drain Current Start-up Profile .............................................................38
12.3 V
OUT
and Drain Voltage Start-up Profile.............................................................39
12.4 Over-Current Protection.....................................................................................40
12.5 VDS & ID at Maximum Power............................................................................41
12.6 Voltage Stress ...................................................................................................41
12.7 Overvoltage Protection (Open-Loop Test) .........................................................42
12.8 Load Transient Response..................................................................................43
12.9 Output Ripple Measurements ............................................................................44
12.9.1 Ripple Measurement Technique.................................................................44
12.9.2 Ripple and Noise Measurement Results ....................................................45
13
Control Loop Measurements .................................................................................47
13.1 115 VAC Maximum Load...................................................................................47
13.2 230 VAC Maximum Load...................................................................................48
14
Conducted EMI .....................................................................................................49
14.1 Output Grounded ...............................................................................................49
14.2 Output Floating ..................................................................................................52
15
AC Surge...............................................................................................................54
15.1 Common Mode Surge, 1.2 / 50
sec .................................................................54
15.2 Differential Mode Surge, 1.2 / 50
sec...............................................................54
16
Appendix A: Fast AC Reset...................................................................................55
17
Appendix B: Circuit Modification for Reduced No-load Input Power and Enhanced
Output OVP Performance .....................................................................................56
17.1 Enhanced Output OVP Latch Sensitivity ...........................................................57
18
Revision History ....................................................................................................58
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.
Page 3 of 59
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
RDR-242 – 30 W Open Frame Supply using TOP266VG
01-Mar-10
1 Introduction
This engineering report describes a power supply employing the Power Integrations
®
TOPSwitch
®
-JX TOP266VG. This power supply operates over a universal input range
and provides a 12 V, 30 W output. It has been designed and tested to operate open
frame with an ambient temperature environment of up to 40 °C.
The TOPSwitch-JX, by design, maintains virtually constant efficiency across a very wide
load range without using special operating modes to meet specific load thresholds. This
optimizes performance for existing and emerging energy-efficiency regulations.
Maintaining constant efficiency ensures design optimization for future energy-efficiency
regulation changes without the need for redesign.
The low MOSFET capacitance of TOPSwitch-JX allows a higher switching frequency
without the efficiency penalty which occurs with standard discrete MOSFET. The 132 kHz
switching frequency (rather than the 70 kHz to 100 kHz frequency used for a discrete
MOSFET) reduces the transformer size required, and so reduces cost.
This power supply offers the following protection features:
Output OVP (including open loop) with latching shutdown
Auto-recovery type overload protection
This document provides complete design details including specifications, the schematic,
bill of materials, and transformer design and construction information. This information
includes performance results pertaining to regulation, efficiency, standby, transient load,
power-limit data, and conducted EMI scans.
Power Integrations, Inc.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 4 of 59
01-Mar-10
RDR-242 – 30 W Open Frame Supply using TOP266VG
Figure 1 –
Populated Circuit Board Photograph, Component Side.
Figure 2 –
Populated Circuit Board Photograph, Solder Side.
Page 5 of 59
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
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