RDK-462

Reference Design Report for a 10 W CV/CC TM Title USB Charger using LinkSwitch -4 LNK4023D 85 VAC 265 VAC Input Specification 5 V, 2 A Output (End of USB Cable) Application Cell Phone / USB Charger Author Applications Engineering Department Document RDR-462 Number Date August 02, 2016 Revision 1.2 Summary and Features LinkSwitch-4 Primary side regulated (no optocoupler) 3% CV, 5% CC regulation <30 mW no-load input power Cable voltage drop compensation Highly optimized BJT drive for low switching loss Comfortably meets European CoC Tier 2, ENERGY STAR 2 and DoE-6 efficiency requirements 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-462 5 V, 2 A LinkSwitch-4 USB Charger 02-Aug-16 Table of Contents 1 Introduction ......................................................................................................... 4 2 Power Supply Specification ................................................................................... 5 3 Schematic ............................................................................................................ 6 4 Circuit Description ................................................................................................ 7 4.1 Input EMI Filtering ......................................................................................... 7 4.1 Primary ......................................................................................................... 7 4.2 Secondary ..................................................................................................... 8 5 PCB Layout .......................................................................................................... 9 6 Bill of Materials .................................................................................................. 10 7 Transformer Specification ................................................................................... 11 7.1 Electrical Diagram ........................................................................................ 11 7.2 Electrical Specifications ................................................................................ 11 7.3 Materials ..................................................................................................... 11 7.4 Transformer Build Diagram .......................................................................... 12 7.5 Transformer Construction ............................................................................. 12 7.6 Transformer Illustrations .............................................................................. 13 8 Transformer Design Spreadsheet ........................................................................ 21 9 Performance Data .............................................................................................. 25 9.1 Active Mode Efficiency (at PCB) vs. Line Voltage ............................................ 25 9.2 Active Mode Efficiency (at End of Cable) vs. Load .......................................... 26 9.2.1 Efficiency vs. Load .................................................................................... 26 9.2.2 Efficiency vs. Light Load (at PCB) .............................................................. 27 9.3 No-Load Input Power ................................................................................... 28 9.4 Average Efficiency ....................................................................................... 29 9.4.1 Average Efficiency at PCB ...................................................................... 29 9.4.2 Average Efficiency at End of Cable ......................................................... 30 9.5 CV/CC Regulation Measured at the End of Cable ............................................ 31 10 Open Case Thermal Performance ........................................................................ 32 11 Waveforms ........................................................................................................ 34 11.1 Load Transient Response (End of Cable) ....................................................... 34 11.2 Load Transient Response (at PCB) ................................................................ 35 11.3 Switching Waveforms ................................................................................... 36 11.4 Start-up Waveform and Delay ...................................................................... 36 11.4.1 Full Load .............................................................................................. 36 11.4.2 Zero Load ............................................................................................. 37 11.5 Output Ripple Measurements ........................................................................ 38 11.5.1 Ripple Measurement Technique ............................................................. 38 11.5.2 Measurement Results ............................................................................ 39 11.5.3 Full Load Ripple Voltage (mV p-p) .......................................................... 39 12 Conductive EMI .................................................................................................. 40 12.1 2 A Resistive Load, Floating Output (QP / AV) ............................................... 40 12.2 2 A Resistive Load, Artificial Hand Ground (QP / AV) ...................................... 42 Power Integrations, Inc. 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