RDK-420 Power Integrations

Reference Design Report for a 10 W CV/ CC TM Title USB Charger using InnoSwitch -CH INN2023K 85 VAC 264 VAC Input Specification 5 V, 2 A Output (end of USB Cable) Application Cell Phone / USB Charger Author Applications Engineering Department Document RDR-420 Number Date April 20, 2015 Revision 1.1 Summary and Features InnoSwitch-CH - Industry first AC/DC ICs with isolated, safety rated integrated feedback All the benefits of secondary side control with the simplicity of primary side regulation 3% CV, 5% CC regulation Insensitive to transformer variation Transient response independent of load timing Smaller, lower cost output capacitors <10 mW no-load input power Cable voltage drop compensation Built in synchronous rectification for high efficiency 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-420 10 W 5 V, 2 A InnoSwitch-CH USB Charger 20-Apr-15 Table of Contents 1 Introduction ......................................................................................................... 4 2 Power Supply Specification ................................................................................... 5 3 Schematic ............................................................................................................ 6 4 Circuit Description ................................................................................................ 7 4.1 Input EMI Filtering ......................................................................................... 7 4.1 InnoSwitch-CH IC Primary .............................................................................. 7 4.2 InnoSwitch-CH IC Secondary .......................................................................... 8 5 PCB Layout .......................................................................................................... 9 6 Bill of Materials .................................................................................................. 11 7 Transformer Specification ................................................................................... 12 7.1 Electrical Diagram ........................................................................................ 12 7.2 Electrical Specifications ................................................................................ 12 7.3 Materials ..................................................................................................... 12 7.4 Transformer Build Diagram .......................................................................... 13 7.5 Transformer Instructions .............................................................................. 13 7.6 Transformer Illustrations .............................................................................. 14 8 Transformer Design Spreadsheet ........................................................................ 18 9 Performance Data .............................................................................................. 21 9.1 Active Mode Efficiency (at USB Socket) vs. Line ............................................. 21 9.2 Active Mode Efficiency (at USB Socket) vs. Load ............................................ 22 9.2.1 Efficiency without Schottky Diode in Parallel with Q1, SR FET .................. 22 9.2.2 Efficiency with a Schottky Diode, SS16, in Parallel with Q1, SR FET .......... 24 9.3 No-Load Input Power ................................................................................... 25 9.4 Average Efficiency (at USB Socket) ............................................................... 26 9.4.1 Efficiency Requirements ........................................................................ 26 9.4.2 Average Efficiency at 115 VAC Input ...................................................... 26 9.4.3 Average Efficiency at 230 VAC Input ...................................................... 27 9.5 CV/CC Regulation Measured at the End of Cable ............................................ 28 10 Open Case Thermal Performance ..................................................................... 29 11 Waveforms ..................................................................................................... 31 11.1 Load Transient Response (end of cable) ........................................................ 31 11.2 Load Transient Response (at USB Socket) ..................................................... 32 11.3 Switching Waveforms ................................................................................... 33 11.3.1 InnoSwitch-CH Waveforms .................................................................... 33 11.3.2 SR FET Waveforms ............................................................................... 33 11.4 Output Ripple Measurements ........................................................................ 34 11.4.1 Ripple Measurement Technique ............................................................. 34 11.4.2 Measurement Results ............................................................................ 35 12 Conductive EMI ............................................................................................... 36 12.1 2 A Resistive Load, Floating Output (PK / AV) ................................................ 36 12.2 2 A Resistive Load, Artificial Hand Ground (PK / AV) ...................................... 38 12.3 Smartphone with Monitor Set-up (HDMI) (QP / AV) ....................................... 40 Power Integrations, Inc. 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