RDK-295 Power Integrations

Reference Design Report for a 20 W Standby TM Title Power Supply Using TinySwitch -4 TNY290PG 90 VAC 295 VAC (110 VDC 420 VDC) Input Specification 5 V, 4 A Output Application General PC Standby Author Applications Engineering Department Document RDR-295 Number Date September 25, 2012 Revision 1.5 Summary and Features TM EcoSmart Meets all existing and proposed harmonized energy efficiency standards including: CECP (China), CEC, EPA, AGO, European Commission No-load consumption <40 mW at 230 VAC >81% active-mode efficiency (exceeds standards requirement of 76%) BP/M capacitor value selects MOSFET current limit for greater design flexibility Output overvoltage protection (OVP) using primary bias winding sensed shutdown feature Precision OVP circuit guarantees precise selection of over voltage detection threshold 2 Tightly toleranced I f parameter (10%, +12%) reduces system cost: Increases MOSFET and magnetics power delivery Reduces overload power, which lowers output diode and capacitor costs Integrated TinySwitch-4 Safety/Reliability features: Accurate (5%), auto-recovering, hysteretic thermal shutdown function maintains safe PCB temperatures under all conditions Auto-restart protects against output short circuit and open loop fault conditions >3.2 mm creepage on package enables reliable operation in high humidity and high pollution environments Meets EN550022 and CISPR-22 Class B conducted EMI The products and applications illustrated herein (including circuits external to the products and transformer construction) 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 5245 Hellyer Avenue, San Jose, CA 95138 USA. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com RDR-295 20 W PC standby Power Supply Using TNY290PG 25-Sep-12 Table of Contents 1 Introduction ................................................................................................................. 4 2 Power Supply Specification ........................................................................................ 5 3 Schematic ................................................................................................................... 6 4 Circuit Description ...................................................................................................... 9 4.1 Input Rectifier and Filter ...................................................................................... 9 4.2 TNY290PG Primary ............................................................................................. 9 4.3 Output Rectification ........................................................................................... 10 4.4 Output Feedback ............................................................................................... 10 4.5 UV Lockout ........................................................................................................ 10 4.6 Overvoltage Protection (OVP) ........................................................................... 11 5 PCB Layout .............................................................................................................. 13 6 Bill of Materials ......................................................................................................... 14 7 Transformer Specification ......................................................................................... 16 7.1 Electrical Specifications ..................................................................................... 16 7.2 Materials ............................................................................................................ 16 7.3 Transformer Build Diagram ............................................................................... 17 7.4 Transformer Construction .................................................................................. 17 7.5 Transformer Illustrations .................................................................................... 18 8 Transformer Design Spreadsheet ............................................................................. 23 9 Performance Data .................................................................................................... 26 9.1 Efficiency 68 F Input Capacitor C2 and Thermistor RT1 in Circuit ............... 26 9.2 Efficiency Without Thermistor RT1 in Circuit (Replaced with a Jumper) ........ 27 9.3 Efficiency 380 VDC Input Right at the 68 F Input Bulk Capacitor ................. 28 9.4 Maximum Output Power .................................................................................... 29 10 80 Plus Average Efficiency Measurement ............................................................ 30 10.1 Input Power at No-Load..................................................................................... 31 10.2 Input Power for 250 mW Load ........................................................................... 32 10.3 Available Standby Output Power ....................................................................... 33 10.4 Regulation ......................................................................................................... 34 10.4.1 Load Regulation ......................................................................................... 34 10.4.2 Line Regulation .......................................................................................... 34 11 Thermal Performance ........................................................................................... 35 12 Waveforms ............................................................................................................ 36 12.1 Drain Voltage and Current, Normal Operation ................................................... 36 12.2 Drain Voltage and Current Start-up Profile ........................................................ 36 12.3 Output Voltage Start-up Profile .......................................................................... 38 12.4 Load Transient Response ................................................................................. 39 12.4.1 Load Step = 75 100 75%, with Soft-Finished Capacitor ....................... 39 12.5 Output Ripple Measurements ............................................................................ 40 12.5.1 Ripple Measurement Technique ................................................................ 40 12.5.2 Measurement Results ................................................................................ 41 12.6 Brown In and Brown Out Test at Full Load ........................................................ 42 13 Line Surge ............................................................................................................. 43 14 Output Overvoltage Shutdown .............................................................................. 44 Power Integrations, Inc. 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