RDK-378 Power Integrations

Reference Design Report for a 7 W Non- Title Dimmable, Non-Isolated Buck LED Driver TM Using LYTSwitch -0 LYT0006D Specification 190 VAC 265 VAC Input 85 V, 82 mA Output Application A17 / A19 LED Driver Lamp Replacement Author Applications Engineering Department Document RDR-378 Number Date October 4, 2013 Revision 1.0 Summary and Features Single-stage power factor corrected ( >0.5 at 230 V) and accurate constant current (CC) output Low cost, low component count and small PCB footprint solution Highly energy efficient, 91% across VAC input range Fast start-up time (<100 ms) no perceptible delay Integrated protection and reliability features Single-shot no-load protection Output short-circuit protected with auto-recovery Auto-recovering thermal shutdown with large hysteresis protects both components and PCB No damage during brown-out conditions Meets IEC ring wave, differential line surge and EN55015 conducted EMI 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-378 7 W Non-Isolated Buck Using LYT0006D 04-Oct-13 Table of Contents 1 Introduction ................................................................................................................. 3 2 Power Supply Specification ........................................................................................ 5 3 Schematic ................................................................................................................... 6 4 Circuit Description ...................................................................................................... 7 4.1 Input EMI Filtering ............................................................................................... 7 4.2 LYTSwitch-0 ........................................................................................................ 7 4.3 Output Rectification ............................................................................................. 7 4.4 Output Feedback ................................................................................................. 7 4.5 No-Load Protection ............................................................................................. 8 5 PCB Layout ................................................................................................................ 9 6 Bill of Materials ......................................................................................................... 10 7 Inductor Design Spreadsheet ................................................................................... 11 8 Performance Data .................................................................................................... 13 8.1 Active Mode Efficiency ...................................................................................... 14 8.2 Output Current Regulation ................................................................................. 15 8.2.1 Output Current Regulation Across Line and Load ...................................... 15 9 Thermal Performance ............................................................................................... 16 9.1 Equipment Used ................................................................................................ 16 9.2 Thermal Result .................................................................................................. 18 9.2.1 Load: 85 V / 82 m A LED Load................................................................. 18 9.3 Thermal Scan .................................................................................................... 19 10 Waveforms ............................................................................................................ 20 10.1 Drain Voltage, Current Normal Operation .......................................................... 20 10.2 Drain Voltage and Current When Output Short ................................................. 21 10.3 Drain Voltage and Current Start-up Profile ........................................................ 21 10.4 Output Current Start-up Profile .......................................................................... 22 10.5 Input-Output Profile ........................................................................................... 23 10.6 Line Sag and Surge ........................................................................................... 24 10.7 One Shot No-Load Protection ........................................................................... 25 10.8 Brown-out / Brown-in ......................................................................................... 26 11 Line Surge ............................................................................................................. 27 12 Conducted EMI ..................................................................................................... 29 13 Revision History .................................................................................................... 32 Important Note: Although this board is designed to satisfy safety isolation requirements, the engineering prototype has not been agency approved. 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 33