EVAL12W3PHSMP7TOBO1 Infineon

AN 201710 PL52 003 12 W three-phase power supply for smart meters and home appliances About this document Author: Stefan Preimel Scope and purpose This document is an engineering report describing a three-phase-input 12 V 12 W Flyback converter power supply using the ICE5QSAG QR Flyback controller and the new 950 V CoolMOS P7 SJ MOSFET IPD95R1K2P7, which are the latest generation of devices from Infineon. The converter is operated in Discontinuous Conduction Mode (DCM) with variable frequency, has a low standby power, and has various protection modes built in for a highly reliable system. This demo board is designed to evaluate the performance of the IPD95R1K2P7 for ease of use in applications such as smart meter power supplies. This board could also be used as an auxiliary power supply for home appliances such as air-conditioning units or induction cookers. Intended audience Power supply designers for smart meters and home appliances. Table of contents Table of contents ............................................................................................................................ 1 1 Overview and key results ................................................................................................ 3 2 Board introduction ........................................................................................................ 7 2.1 DCM Flyback (fixed frequency) ............................................................................................................... 8 2.2 QR Flyback (variable frequency) ............................................................................................................. 9 2.3 Unique features of the fifth-generation QR controller ......................................................................... 11 2.3.1 Fast self-start-up and sustaining of V ........................................................................................... 11 CC 2.3.2 QR switching with valley sensing..................................................................................................... 11 2.3.3 System robustness and reliability through protection features .................................................... 11 2.3.3.1 Input voltage monitoring and protection .................................................................................. 11 2.3.3.2 Other protections with auto-restart ........................................................................................... 11 2.4 Demo board protection features .......................................................................................................... 11 3 Board specifications ...................................................................................................... 13 4 Build information ......................................................................................................... 14 4.1 Schematic .............................................................................................................................................. 14 4.2 Board layout .......................................................................................................................................... 15 4.3 Bill of Materials ...................................................................................................................................... 15 4.4 Transformer specification ..................................................................................................................... 17 5 Circuit description ........................................................................................................ 19 5.1 EMI filtering and line rectification ......................................................................................................... 19 5.2 Flyback converter power stage ............................................................................................................. 19 5.3 Control of Flyback converter through fifth-generation QR controller ICE5QSAG ............................... 19 5.3.1 PWM control and switching MOSFET ............................................................................................... 19 5.3.2 Current sensing ................................................................................................................................ 19 5.3.3 FB and compensation network ....................................................................................................... 19 Application Note ImportantNotice 1.0 www.infineon.com/P7 2019-05-02 12 W three-phase power supply for smart meters and home appliances Table of contents 5.4 Clamping circuit .................................................................................................................................... 20 5.5 PCB design hints .................................................................................................................................... 20 5.6 EMI reduction hints ............................................................................................................................... 21 6 Test results .................................................................................................................. 22 6.1 Connections and initial power-up ........................................................................................................ 22 6.2 Start-up .................................................................................................................................................. 22 7 Protections, reliability and EMI ...................................................................................... 24 7.1 Output short protection ........................................................................................................................ 24 7.2 Breakdown voltage headroom ............................................................................................................. 26 7.3 Surge waveforms ................................................................................................................................... 27 7.4 EMI test results (conducted and radiated) ........................................................................................... 28 7.4.1 Conducted EMI ................................................................................................................................. 28 7.4.2 Radiated EMI..................................................................................................................................... 29 8 Performance comparison results .................................................................................... 32 8.1 Efficiency and thermals (185 V AC single-phase input) ................................................................... 32 in 8.2 Efficiency and thermals (380 V AC three-phase input) .................................................................... 34 in 9 Thermal performance ................................................................................................... 36 10 Portfolio ...................................................................................................................... 38 11 Further cost-lowering potential by using SOT-223 ............................................................ 39 12 Conclusion ................................................................................................................... 41 13 References ................................................................................................................... 42 Revision history............................................................................................................................. 43 Application Note 2 1.0 2019-05-02