Reference Design Report for a 12 W Non- Isolated, Buck Topology, Power Factor Title TM Corrected, LED Driver Using LinkSwitch -PH LNK405EG Specification 90 VAC 265 VAC Input 36 V, 330 mA Output Application LED Driver Author Applications Engineering Department Document RDR-257 Number Date January 6, 2011 Revision 1.0 Summary and Features Dramatically simplifies off-line, power factor corrected, LED driver design Single-stage, power factor corrected, non-isolated LED driver Compact with extremely low component count High power factor >0.9 across line and load Very high efficiency >85%, 87% typical Low THD, <20% at 230 VAC No output current sensing required Advanced performance features Compensates for inductance tolerance Compensates for input voltage variations Compensates for output voltage variations Frequency jittering greatly reduces EMI filter costs Advanced protection and safety features Auto-restart protection for short-circuit Hysteretic thermal shutdown 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-257 12 W Non-isolated BUCK LED Driver Using LNK405EG 06-Jan-11 Table of Contents 1 Introduction................................................................................................................. 4 2 Power Supply Specification ........................................................................................ 7 3 Schematic................................................................................................................... 8 4 Circuit Description ...................................................................................................... 9 5 PCB Layout ...............................................................................................................10 6 Bill of Materials ..........................................................................................................11 6.1 Electrical.............................................................................................................11 6.2 Optional OVP Circuit ..........................................................................................11 6.3 Mechanical .........................................................................................................12 7 Heat Sink Assembly ..................................................................................................13 8 Inductor Specification ................................................................................................14 8.1 Electrical Diagram ..............................................................................................14 8.2 Electrical Specifications......................................................................................14 8.3 Materials.............................................................................................................14 8.4 Inductor Build Diagram.......................................................................................14 9 Performance Data .....................................................................................................15 9.1 Efficiency............................................................................................................15 9.2 Line and Load Regulation...................................................................................16 9.3 Power Factor......................................................................................................17 9.4 THD....................................................................................................................18 9.5 Harmonics ..........................................................................................................19 9.6 Test Data............................................................................................................21 9.6.1 Test Data, 13 LED Load.............................................................................21 9.6.2 Test Data, 12 LED Load.............................................................................21 9.6.3 Test Data, 11 LED Load.............................................................................21 9.6.4 230 VAC, 50 Hz Harmonics Data, P = 14.529 W.....................................22 IN 9.6.5 115 VAC, 60 Hz Harmonics Data, P = 13.96 W.......................................23 IN 10 Waveforms ................................................................................................................24 10.1 Input Line Current...............................................................................................24 10.2 Drain Voltage and Current Normal Operation.....................................................25 10.3 Drain Voltage and Current Start-up Operation ...................................................26 10.4 Output Current, Normal Condition, V ~ 36 V .................................................27 OUT 10.5 Output Current Ripple, V ~ 36 V....................................................................28 OUT 10.6 Output Current and Voltage at Power-up, Power-down .....................................29 10.7 Output Short.......................................................................................................30 10.8 Open Load/LED Condition..................................................................................30 11 Thermal Measurements.............................................................................................31 11.1 Thermal Test Set-up...........................................................................................31 11.2 Thermal Test Results .........................................................................................31 12 Conducted EMI Measurements .................................................................................32 12.1 Conducted EMI Test Set-up ...............................................................................32 12.1.1 Configuration A: Solder Side of Driver Facing Grounded T8 Fixture..........32 12.1.2 Configuration B: Component Side of Driver Facing Grounded T8 Fixture..33 12.2 Conducted EMI Test Results..............................................................................34 Power Integrations Tel: +1 408 414 9200 Fax: +1 408 414 9201 www.powerint.com Page 2 of 40