RDK-321

Reference Design Report for a 17 W Dual Title Output Flyback Converter for LCD Monitor TM Using LinkSwitch -HP LNK6774V 90 VAC 265 VAC Input Specification 5 V, 1 A and 18 V, 670 mA Output Application LCD Monitor Author Applications Engineering Department Document RDR-321 Number Date September 28, 2012 Revision 2.2 Summary and Features Primary-side regulated isolated flyback converter with 5% regulation 132 kHz switching frequency for small transformer and output filter size Full load continuous conduction mode operation for improved efficiency and reduced output capacitor ripple currents Multimode operation maximizes efficiency over full load range Below 100 mW input power with 50 mW standby load at 230 VAC Extensive protection features including OVP, OTP, brown-in/out, line overvoltage, and lost- regulation (auto-restart) Meets EN-550022 and CISPR-22 Class B conducted EMI Meets IEC61000-4-5 1 kV / 2 kV surge 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-321 17 W Dual Output Flyback Supply for LCD Monitor 28-Sep-12 Table of Contents 1 Introduction ................................................................................................................. 4 2 Power Supply Specification ........................................................................................ 5 3 Schematic ................................................................................................................... 7 4 Circuit Description ...................................................................................................... 8 4.1 Input Rectification and Filtering ........................................................................... 8 4.2 LinkSwitch-HP Primary ........................................................................................ 8 4.3 Primary RCD Clamp ............................................................................................ 8 4.4 Output Rectification ............................................................................................. 9 4.5 External Current Limit Setting .............................................................................. 9 4.6 Feedback and Compensation Network ............................................................... 9 5 PCB Layout .............................................................................................................. 10 6 Bill of Materials ......................................................................................................... 11 7 Transformer Design Spreadsheet ............................................................................. 12 8 Transformer Specification ......................................................................................... 16 8.1 Electrical Diagram ............................................................................................. 16 8.2 Electrical Specifications ..................................................................................... 16 8.3 Materials ............................................................................................................ 16 8.4 Transformer Build Diagram: .............................................................................. 17 8.5 Transformer Construction: ................................................................................. 17 8.6 Transformer Illustrations: ................................................................................... 18 9 Performance Data .................................................................................................... 25 9.1 Active Mode Efficiency ...................................................................................... 25 9.2 Input Power at Standby and Standby Efficiency ................................................ 27 9.3 Line Regulation at 18 V 0.67 A DC Load and 5 V 1 A Average Load ................ 29 9.4 Output Voltage under Specified Dynamic Load Profile Including Peak, Minimum and Mean Value ........................................................................................................... 31 9.4.1 Test Method for Peak and Minimum Output Voltage .................................. 31 9.4.2 5 V Output Voltage under Specified Load Profile ....................................... 32 9.4.3 18 V Output Voltage under Specified Load Profile ..................................... 36 10 Thermal Performance ........................................................................................... 40 11 Waveforms ............................................................................................................ 42 11.1 Drain Voltage and Current, Normal Operation ................................................... 42 11.2 Drain Voltage and Current Start-up Profile ........................................................ 42 11.3 Output Voltage Start-up Profile with Input Voltage ............................................ 43 11.4 5 V Load Transient Response ........................................................................... 44 11.4.1 5 V Transient Tested with 5 V 500 mA to 1500 mA Step Load and Fixed 18 V, 0.67 A DC Load .................................................................................................... 44 11.4.2 5 V Transient Tested with Specified Load Profile ....................................... 45 11.4.3 18 V Transient Tested with Specified Load Profile ..................................... 46 11.5 Output Ripple and Noise Measurements ........................................................... 47 11.5.1 Ripple Measurement Technique ................................................................ 47 11.5.2 Ripple of 18 V Tested at 18 V Maximum Load and 5 V 1 A Steady Load 48 11.5.3 Ripple of 5 V Tested at 18 V Maximum Load and 5 V 1 A Steady Load .... 49 12 Protection Feature ................................................................................................ 50 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 2 of 56