RDK-242

Reference Design Report for a 30 W Supply Title Using TOPSwitch -JX TOP266VG Specification 85 VAC 264 VAC Input 12 V, 2.5 A Output Application General Purpose Author Applications Engineering Department Document RDR-242 Number Date March 1, 2010 Revision 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 ) and use of 60 V Schottky output diode OR 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 <RDR-242 30 W Open Frame Supply using TOP266VG 01-Mar-10 Table of Contents 1 Introduction.................................................................................................................4 2 Power Supply Specification ........................................................................................6 3 Schematic...................................................................................................................7 4 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. 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