SiC Solution for Industrial Auxilliary Power Supply 05122017 Christian Felgemacher Application Engineer Power Systems Department
ROHM s Power Devices ROHM s power item lineup covers wafers/bare dies, discrete packages, module, ICs and Intelligent Power Modules Device SiC (SBD/MOSFET) Today we focus on an auxilliary IGBT supply solution around discrete Hybrid MOS SiC MOSFETs and driving/control IC Super Junction MOSFET FRD SBD Shunt Resistor Discrete TO220 TO247/3PF D-Pak / D2-Pak etc Power Module Case type (Full SiC Module) Mold type IPM etc ICs Gate driver Temperature/High Voltage monitor ACDC etc P 1
ROHM s power devices 50+ years experience in Si Transistors/Diodes, 15+ years in WBG Semiconductors Material Si SiC GaN Device Breakdown Voltage SJ MOSFET 500V~ 800V Hybrid MOSFET 600V* 300V 600V 1200V* FRD IGBT SBD MOSFET HEMT 430V 650V 1200V* 650V 1200V 1700V 650V 1200V 1700V R&D* *in development P 2
Myths of SiC MOSFET technology Expensive Device cost may be higher, but overall system cost equal or lower P 3
Application advantages vs Si components Lower Resistance Smaller Size / Higher Efficiency Si SiC Higher Frequency Operation Smaller Passive Components Si SiC Higher Temp Operation Simpler Cooling System Si 250 200 SiC V GS=18V 16V 14V Down sizing 12V 150 10V 8V 100 6V 4V 2V 50 0V 0 0 5 10 15 20 P 4
Myths of SiC MOSFET technology Expensive Not reliable Device cost may be higher, but overall system cost equal or lower Extensive reliability testing done, comparable to Sibased devices P 5
Reliability aspects of SiC Trench MOSFETs Reliability tests for ROHM Trench MOSFETs Test IEC Standard Conditions Si SiC Comments SiC High Temperature Reverse Bias High Temperature Gate Bias High Humidity High Temperature Reverse Bias High Temperature Storage Low Temperature Storage 60747 60747 60068-67 1000 h @ 95% V ds,max, T amb = 125145 C 1000 h @ ±V GS,max, T amb = T j,max SiC 3 Gen MOSFETs undergo reliability1000 tests h @ similar V ds,max =80V to those for Si MOSFETs 85% RH, T amb = and 85 CIGBTs Automotive qualification soon to be finished 60068-2-2 1000 h @ T STG,max 60068-2-1 1000 h @ T STG,min @ 100% V ds,max T amb = T j,max =175 C V ds,max =100V Thermal Cycle 60068-2-14 100 cycles T STG,max - T STG,min P 6
Myths of SiC MOSFET technology Expensive Not reliable Complex Device cost may be higher, but overall system cost equal or lower Extensive reliability testing done, comparable to Sibased devices Use of SiC MOSFETs can simplify circuit design Todays focus: Simple solution for aux supply P 7
Auxiliary power supplies for industrial applications System (PV inverter, DC/DC converter, battery charger, etc) INPUT Main converter OUTPUT Auxiliary power supply 24V 12V 5V LV subsystems (ie control units, sensors, human interfaces, gate drivers) Auxiliary voltage separated from the main power path High voltage input Low voltage output Isolated P 8
Typical circuit for industrial auxilliary supply Flyback converter with 3-phase input Reflected voltage from secondary side V refl AC mains 3ph V ac,in = 210 690V V dc,in 300 1000V 100V Q What is the max voltage the MOSFET has to withstand? V surge 200V (turn-off overshoot) V dc,in + V refl + V surge = 1300V Device rated voltage: 1500 V P 9
Typical Si-based solutions Q2 Q Q1 Q1 1500V Si MOSFET eg 1500V, 6Ω Q2 Series connection of 800V Si MOSFETs Two-switch flyback topology High gate charge Qg (high gate driving losses) High leakage current, especially at high temp High conduction losses Gate driving circuit more complex Static voltage balancing network Larger space for the heat sink Higher complexity in design and assembly Isolated gate driver & power supply for high side Larger space for the heat sink P 10
Why use a SiC-MOSFET in this application? Si-MOSFET-A Si-MOSFET-B Si-MOSFET-C Property unit SCT2H12NZ 2SK225 STFW3N150 NDUL09N150C min typ max min typ max min typ max min typ max V(BR)DSS V 1700 1500 1500 1500 Id @ 25 C A 3,7 2 2,5 6 Rds(on)@25 C Ω 1,15 1,5 9 12 6 9 2,2 3 Idss@25 C µa 0,1 10 500 10 1000 Ciss pf 184 990 939 2025 Rg Ω 64 4 Qg nc 14 29,3 114 Rth(j-c) K/W 3,32 4,32 2 SiC MOSFET has lower R DS(on) Also, Qg and capacitance are much reduced High gate resistance of SiC device demands a low-impedance gate drive P 11
Why use a SiC-MOSFET in this application? The underlying advantage is the significantly reduced R DS(on) A value of SiC MOSFETs vs Si-MOS P 12
ROHM SiC-MOSFETs for Auxiliary Power Supplies Lineup 1700V SiC MOSFET devices: NEW NEW Part No R V DS [V] DSon typ [mω] @Vgs=18V I D [A] @T C =25 C I D [A] @T C =100 C T jmax[ C] Package Die Part No SCT2H12NZ 1700 1150 3,7 2,6 175 TO-3PFM - SCT2H12NY 1700 1150 4,0 2,9 175 TO-268-2L - SCT2750NY 1700 750 5,9 4,0 175 TO-268-2L - 1700 100 34-175 bare die S2409 P 13
SiC MOSFET in auxiliary power supplies SiC-based solution with 1700V MOSFET and singleswitch flyback topology Single switch Isolated package Control IC BD768xFJ Heat sink not mandatory if <40W TO-268 2L 075Ω, 115Ω Input: Output: Power: Sw freq: 300-900 Vdc 12 Vdc 40 W (no heat sink) 90 120 khz ROHM evaluation board available BD7682FJ_EVK_301 Efficiency: 85% (300 Vdc), 83% (700 Vdc) BD768xFJ 80mm Q TO-3PFM 115Ω SCT2H12NZ 80mm P 14
85-265Vac Diode Bridge BO ZT VCC FB MASK CS OUT GND RS 巻線比 :NP VP VD 巻線比 :ND VS 巻線比 :NS PC CM ERROR AMP VOUT BD768xFJ-LB s features Feature Optimum System for driving SiC MOSFET Quasi Resonant DC/DC convertor Low VCC current (19uA@VCC=185V) Burst function at light load Max Frequency Controlled(120kHz) VCC Over Voltage Protection VCC Under Voltage Locked Out Brown IN/OUT Function DC/DC Soft Start DC/DC Cycle by Cycle current limiter 250nsec Leading-Edge Blanking ZT Trigger mask function ZT Over Voltage Protection Over Load Protection ( 128ms Timer ) MASK Function AC + - FUSE Filter Application circuit 8 7 6 Control IC 5 1 2 3 4 Specification Operating VCC Range : 150V ~ 275V DCDC Max Frequency : 120kHz Operating current 800 ua Operating Temperature: - 40deg to +105deg NO Pin PIN place / Package 1 ZT Zero Current Detect pin 2 FB Feedback pin 3 CS Current Sense pin 4 GND GND pin 5 OUT MOSFET drive pin 6 MASK External TR drive 7 VCC Power Supply pin 8 BO Broun IN/OUT monitor pin Application Factory Automation, Adaptor, Smart Meter Line up FBOLP VCCOVP BD7682FJ AutoRestart Latch BD7683FJ Latch Latch BD7684FJ AutoRestart AutoRestart BD7685FJ Latch AutoRestart SOP-J8S 60mm 49mm : 127mm pitch <TYP> P 15
SiC MOSFET in auxiliary power supplies Reduced effective switching voltage leads to lower turn-on loss ROHM evaluation board BD7682FJ_EVK_301 Control IC for SiC based solution: BD768xFJ Implements quasi-resonant switching to minimise dynamic losses and achieve low noise Suitable drive voltage for SiC MOSFET P 16
SiC MOSFET in auxiliary power supplies Waveforms of flyback switch for different operating contitions: Quasi-resonant operation is maintained across the output power range As the delay time decreases the effective switching frequency increases with increased load P 17
SiC MOSFET in auxiliary power supplies Operation at 40W without heat sink (with heat sink ca 100W possible) V out = 12 V DC Sp1 Sp3 Sp2 P 18
3 4 5 6 Next step: Integration of SiC MOSFET and controller FUSE Filter Diode Bridge SOURCE FB GND ZT BO VCC DRAIN 1 2 7 ERROR AMP PIN place / Package NO Pin 1 DRAIN DRAIN pin 2 SOURCE Current Sense pin 3 FB Feedback pin 4 GND GND pin 5 ZT Zero Current Detect pin 6 BO Broun IN/OUT monitor pin 7 VCC Power Supply pin Application Factory Automation, Adaptor, Smart Meter Target Specification Operating VCC Range : 150V ~ 295V Operating DRAIN Range ~ 1700V Drain Current ( Continuous ) 4A Drain Current ( Pulsed ) 10A Drain-Source on resistance ca 16 Ohm Power Range ( Without Heat-Sink) ca 30W Power Range ( With Heat-Sink ) ca 100W P 19
+ + + + + + + + + + - Next step: Integration of SiC MOSFET and controller Additional features (tbc) Block diagram VCC Over Voltage Protection VCC Under Voltage Lock Out Soft Start Cycle by Cycle current limiting Burst function Over-load protection Brown-out Gate voltage clamping FUSE Czt Rzt1 Rzt2 Filter Diode Bridge ZT 5 FB 3 Cfb RH Rstart RL Cvcc 6 7 BO VCC BO Comp - 15uA VCC UVLO 10V 185V/140V NOUT - ZT ACSNS Comp - VCC OVP - ZT OVP Comp (LATCH) 280V ZT Comp 1 shot - AND OR TimeOut 7V ( 15 usec ) 100mV ZT Blanking AND OUT(H->L) /400mV 060us NOUT OR MAX Blanking Frequency VREF(4V) - (120kHz) 100V 20k Burst Comp - 050V OLP Timer FBOLP_OH - (128ms) 40V 180V Regulator Internal Clamper Supply OSC OSC POUT S Q PRE FBOLP_OH AND Driver NOUT R VH Va DRAIN 1 VOUT ERROR AMP Soft Start etc 200kΩ 200kΩ DCDC Comp FB/2-100V - + SS1ms SS4ms CURRENT SENSE (V-V Change) Normal : 10 Leading Edge Blanking SOURCE 2 RS 4 GND PC P 20
Conclusions Auxilliary supply solution using BD768xFJ with 1700V SiC MOSFET is a good alternative to auxilliary supply circuits that today use series connection of Si MOSFETs or complex topologies to achieve the desired blocking voltage level Taking advantage of SiC device benefits cost advantages can be realised on the system level The next development step for SiC based auxilliary supply solutions is integration of the control IC and power switch in one package P 21