RDK-623

Reference Design Kit for a Low Standby Title Current Non-Isolated Flyback Power Supply TM Using LinkSwitch -TN2 LNK3202D 85 VAC 277 VAC Input Specification 3.8 V / 20 mA and 12 V / 20 mA Outputs Application Home and Building Automation Author Applications Engineering Department Document RDR-623 Number Date May 24, 2018 Revision 1.4 Summary and Features Highly integrated solution with LNK3202D Low component count with integrated 725 V MOSFET, current sensing and protection Wide range AC input <65 A standby input current across AC line Two outputs, 3.8 V (5%) and 12 V (10%) <7 mW no-load input power at 115 VAC <12 mW no-load input power at 230 VAC Load short-circuit protection EN55022B conducted EMI compliant 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-623 LinkSwitch-TN2 Low Standby Current Power Supply 24-May-18 Table of Contents 1 Introduction ............................................................................................................ 4 2 Power Supply Specification ...................................................................................... 5 3 Schematic ............................................................................................................... 6 4 Circuit Description ................................................................................................... 7 4.1 Input Rectifier, Protection and EMI Filtering ....................................................... 7 4.2 LinkSwitch-TN2 Primary Side and Main Output Circuit Operation ......................... 7 4.3 Regulation of Slave Output ................................................................................ 7 4.4 Output Side and Feedback Loop ........................................................................ 7 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 Material List ................................................................................................... 11 7.4 Transformer Build Diagram ............................................................................. 12 7.5 Transformer Instructions ................................................................................. 12 7.6 Transformer Winding Illustrations .................................................................... 13 8 Transformer Design Spreadsheet ........................................................................... 17 9 Performance Data ................................................................................................. 20 9.1 Full Load Efficiency vs. Input Line Voltage ........................................................ 20 9.1.1 Efficiency vs. Line Voltage, 0.3 W (20 mA on 12 V, 20 mA on 3.8 V) ........... 20 9.2 No-Load Input Power ...................................................................................... 21 9.3 Various Load Current vs. Input Line Voltage ..................................................... 22 9.4 Input Current at Standby vs. Input Line Voltage ............................................... 23 9.5 Line and Load Regulation ................................................................................ 24 9.5.1 12 V Line Regulation at 0.3 W (20 mA on 12 V, 20 mA on 5 V) ................... 24 9.5.2 3.8 V Line Regulation at 0.3 W (20 mA on 12 V, 20 mA on 3.8 V) ............... 25 9.5.3 3.8 V Regulation with Varying Load (12 V Unloaded) .................................. 26 10 Thermal Performance ............................................................................................ 27 10.1 Open Case ..................................................................................................... 27 10.2 85 VAC at Room Temperature ......................................................................... 27 10.3 265 VAC at Room Temperature ....................................................................... 29 11 Waveforms ........................................................................................................... 31 11.1 3.8 V Output Load Transient Response ............................................................ 31 11.2 12 V Output Load Transient Response ............................................................. 31 11.3 Switching Waveforms ...................................................................................... 32 11.3.1 Drain to Source Voltage and Current during Normal Operation .................... 32 11.3.2 Drain to Source Voltage and Current Waveforms during Start-up ................ 33 11.3.3 Input and Output Voltages Waveforms during Start-up .............................. 34 11.3.4 Output Short Auto-Restart ........................................................................ 36 11.4 Output Ripple Measurements ........................................................................... 37 11.4.1 Ripple Measurement Technique ................................................................ 37 Power Integrations, Inc. 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