RDK-131

Reference Design Report for 3 W Non- Title Isolated Constant Current LED Driver Using LNK306DN Specification 85265 VAC Input, 10 V, 300 mA Output Application LED Lighting / Bulb Retrofit Author Power Integrations Applications Department Document RDR-131 Number Date March 7, 2007 Revision 1.1 Summary and Features Extremely small form factor, fits within GU10 lamp base Operates over the universal input voltage range (85 265 VAC) Meets EN55022 B conducted EMI requirements Drives LEDs in constant current (CC) mode Built-in, output overvoltage protection when unloaded Allows supply to be tested without the load connected Low parts count, low-cost solution: only 25 components Non-isolated buck converter configuration allows use of off-the-shelf inductors (does not require a custom transformer) 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-131 LED Driver LNK306DN 7-Mar-07 Table of Contents 1 Introduction...............................................................................................................3 2 Power Supply Specification ......................................................................................5 3 Circuit Diagram.........................................................................................................6 4 Circuit Description ....................................................................................................7 4.1 Configuration and Assembly Details..................................................................7 4.2 AC Input Rectification........................................................................................7 4.3 LinkSwitch-TN ...................................................................................................7 4.4 Output Feedback...............................................................................................7 5 Bill of Materials .......................................................................................................10 5.1 Filter Board Bill of Materials.............................................................................10 5.2 Converter Board Bill of Materials.....................................................................11 6 PI Xls Design Spreadsheet.....................................................................................12 7 Performance...........................................................................................................14 7.1 Efficiency.........................................................................................................14 7.2 Output Current Regulation Vs. Line Voltage....................................................15 7.3 Output VI Characteristic ..................................................................................15 8 Waveforms .............................................................................................................16 8.1 Drain Voltage and Current, Normal Operation.................................................16 8.2 Output Current and Voltage.............................................................................16 8.3 Drain Current and Bulk Capacitor Voltage.......................................................17 8.4 Startup Drain Current and Bulk Capacitor Voltage..........................................17 8.5 Startup Output Voltage and Current ................................................................18 8.6 Fault Conditions ..............................................................................................18 9 Thermal Measurements..........................................................................................19 10 Conducted EMI.......................................................................................................20 10.1 Competitive Product EMI.................................................................................21 11 Revision History......................................................................................................22 Important Note: This board has no safety isolation. Therefore, all testing should be performed using an isolation transformer to provide the AC input to the prototype board. Power Integrations, Inc. Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 2 of 24