ST SiC MOSFET Evolution in Power Electronics

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1 ST SiC MOSFET Evolution in Power Electronics Simone Buonomo Market & Application Development Manager Power Transistor Division Power Transistor Division

2 Agenda 2 SiC MOSFET Time Speaker Why SiC MOSFET? Simone Buonomo ST SiC MOSFET at a glance SiC MOSFET vs other SiC alternatives Conclusions

3 Key Topics 3 Why SiC MOSFET? New Compaunds materials Application Map Advantages vs Standard Silicon Technical positioning ST SiC MOSFET at a glance Product development Schedule First product main electrical parameters SiC MOSFET vs other SiC alternatives driving «needs» MOSFET vs JFET vs BJT MOSFET: simplest driving A look to the diode Conclusions

4 Why SiC MOSFET? Presentation Title 26/09/2012

5 Pw 1 MW GaN SiC SiC & GaN Application Map RAIL TRACTION SMART POWER GRID WIND MILLS kw 100 kw 50 kw 30 kw HEV / EV PHOTOVOLTAIC INDUSTRIAL DRIVES HEV / EV PHOTOVOLTAIC 5kW 1kW NETCOM, SERVER, NOTEBOOK POWER SUPPLY HOME APPLIANCE 600V 1000V 1200V Rated Voltage

6 Why SiC MOSFET: Advantages vs. Standard Silicon 6 1,200V SILICON BASED SWITCHES HAVE REACHED THEIR PRACTICAL LIMITS: IGBT shows high power switching losses above 15 khz Standard and even SuperJunction MOSFETs still exhibit high RDSon at BV > 1,000V SiC MOSFETs allows a dramatic RDSon reduction temperature) as well as much Lower Switching Losses almost indipendent of Temperature even at high junction SiC Technology improves Thermal Performances and can safely withstand much higher working junction temperature versus the silicon based devices.

7 Why SiC MOSFET: Advantages vs Silicon IGBT SiC MOSFET vs. Best in Class IGBT Results measured on first samples (1200V / 30A/100m ) SiC Benefits: Device SiC MOSFET Vcesat typ (Ω)(@ 25 C, 20A Vcesat typ (Ω) (@ 175 C, 20A Eon 20A, 900V 25 C/175 C 20A, 900V 25 C/175 C Chip size / 965(*) 245/ IGBT / / (*) Eon measured by using the SiC intrinsic body diode Increased switching frequency above 100kHz will reduce passive components size and cost Very high temperature operation capability Higher current density Very low Switching losses, small variation vs. temperature Intrinsic body diode as fast as a SiC diode with an higher Vf (~ 3V) Huge switching energy difference Much higher switching frequency is now possible

8 Why SiC MOSFET: A quick look to SuperMESH 5, best in class FETs in Si technology R DS(on) MAX (Ω) 1200V Benchmark 2,4 0,69 0,95 0,32 SuperMESH5 * Simulated data Best Competitor SuperMESH5 Best Competitor 8

9 Why SiC MOSFET: A quick look to SuperMESH 5, best in class FETs in Si technology Targets* by Package/Voltage R DS(on) MAX (mω) 950V 1050V 1200V ISOTOP Max TO TO-3PF TO DPAK As an example to realize a 100mΩ device you need a quite huge chip size. As a natural conseguence you will need a powerful driving due to high Gate Charge. Dynamic perfomance cannot be excellent as a matter of fact. Is the Si state of the art not enough for your application? SiC MOSFET is the right answer!

10 ST SiC MOSFET at a glance Presentation Title 26/09/2012

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15 15 SiC Power MOSFET: 1 st Gen product in development On Resistance vs. Temperature 15 Just 30% higher Ron at 200 C!!

16 SiC MOSFET vs other SiC alternatives Driving needs and switching performances Presentation Title 26/09/2012

17 Different structures in the SiC World 17 The introduction of SiC technology for switching devices rapresents a revolutionary change in the power conversion scenario. Today, three SiC switch technologies (1200V) are offered: SiC JFET SiC BJT SiC MOSFET

18 Three Different SiC Switches under comparison The target of this work is to compare three different switch tecnologies, both unipolar and bipolar, in terms of driving approach and dynamic losses under the same test conditions. Ron C Ron C NORMALIZED AREA +10% 1200V SiC MOSFET 200 mω (@20V,20A) 220 mω (@20V, 20A) 1 +30% 1200V SiC BJT 90 mω (@6A,130mA) 120 mω (@6A,130mA) % 1200V N-OFF SiC JFET 80 mω (3V,12A) 200 mω (3V,12A) 0.7 We chose to compare three normally-off power switches, due to the higher level of complexity imposed by normally-on devices over the entire system. Direct comparison among different technologies in Silicon Carbide 26/09/2012

19 Driving SiC JFET (1/2) 19 SiC normally off JFET Driving needs Special voltage shape for fast turn-on and correct conduction operation. 15V for a very short time (100/200ns) and 3V with right current control after turn-on DC current to the gate during conduction is highly dependent on junction temperature. At 25 C, 20mA are enough, at 100 C it needs 50mA, and at 125 C up to 200mA. (100mΩ device) Gate threshold is positive but it is too low and decreases increasing Tj. To assure a fast and safe turn-off a negative voltage is mandatory. As suggested in AN SS1 by Semisouth

20 Driving SiC JFET (2/2) 20 In the following pictures you can observe the V GS =3V vs V GS =15V (limited time) / 3V SJEP120R063 (SemiSouth JFET) Turn Vcc=600V, Ic=12A Vce EON=365µJ -10V +3V 0V Pd=Vce*Ic Vce EON=190µJ Ic Pd=Vce*Ic +15V +3V 0V Ic -10V

21 SiC BJT Driving needs Driving SiC BJT Quite high peak current is requested for a fast BJT turn-on. Higher than the one needed by JFET. Despite the high hfe of last SiC BJT, a constant DC current has to be provided to the base to achieve the right saturation level (means low VCESAT). As for the JFET the BJT prefers a negative driving to minimize turn-off energy and safely keep the OFF state. Device C1 (nf) EON (µj) 80 mω N-OFF JFET 6A V BJT (R oneq = 90mΩ)

22 Driving SiC MOSFET The easiest driving approch 22 Driving a SiC MOSFET is almost as driving a Si MOSFET with a single exception: Vgs to provide to get the right Rdson is higher than the one you need to drive a Si Devices: Today we have to use a 20V Vgs to obtain the lower Rdson. Very simple and very mature gate driver can be used. ST TD350 is an example. Switching speed is higher than the other SiC solutions Negative driving voltage is not mandatory neither to turn-off nor to safely keep the device in OFF state. In fact gate-source threshold voltage is aligned with the one of standard Silicon devices. Negative voltage is suggested only when drain current is high (>50A) to avoid any possible undesired turn-on due to gate voltage oscillations. This is also a commonly used approach with silicon switches used at high current (IGBT)

23 Switching performances: some snapshots SiC MOSFET SiC BJT Turn 600V 23 v gs v ds Qg tot =32.3nC I b I g Eon=28.5 µj I-V cross 20ns v be I d I c v ce Normally off SiC JFET Qg tot =168nC I g v gs +100% Eon=61 µj I-V cross 48ns I d Qg tot =124nC Eon=45.6 µj I-V cross 24ns +50%

24 Switching performances: some snapshots SiC MOSFET SiC BJT Turn 600V 24 v gs v ds v be v ce I g I b I d Qg tot =35.3 nc Eoff 30 µj I c I-V cross 50ns Normally off SiC JFET v gs +100% Qg tot 73nC Eon= 62.7µJ I-V cross 64ns I g Qg tot =49nC Eoff=70.5 µj I-V cross 105ns +130% v ds I d

25 Driving and switching caracteristics summary ON STATE (Id/Ic=5A, 25 C) INPUT VOLTAGE RANGE TURN ON (Ic/Id=5A, Vds/ce=600V, Tj=25 C TURN OFF (Ic/Id=5A, Vds/ce=600V, Tj=25 C TURN OFF VOLTAGE SiC MOSFET Ig[mA] Vgs[V] Vgs th Vgs typ Qgs tot Eon Qgs tot Eoff Vdr 1200V, 200mΩ [V] [nc] [µj] [nc] [µj] [V] SiC BJT Ib[mA] Vbe[V] Vbe min Qbe tot Eon Qbe pk Eoff Vdr 1200V, 80mΩ [V] [nc] [µj] [nc] [µj] [V] n-off SiC JFET 1200V, 90mΩ Ig[mA] Vgs[V] Vgs th Vgs max [V] Qgs tot [nc] Eon [µj] Qgs pk [nc] Eoff [µj] Vdr [V] SiC shows much better dynamic performance still being driven as a standard MOSFET

26 Paper presented at PCIM For further info on how to drive SiC devices please have a look to the above paper

27 Last but not least...what about Freewheeling diode? MOSFET is the only SiC structure to offer intrinsic body diode. Intrinsic Body diode is an ideal diode. It is a SiC diode by nature Freewheeling path in inverters can be one of the following: Through intrinsic diode (High Vf 3V) Through channel by turning MOSFET on and using in the third quadrant Using a SiC JBS external or co-pack freewheeling diode

28 Conclusions 28 Key features Industry Leading Rdson Simple to Drive Body Diode with No Reverse Recovery Charges Very low switching losses with slighty dependance ontemperature Value propositions Smaller Form Factor Lighter Systems Save Size/Cost of Passive Components Higher Systems Efficiency Reduced Cooling Requirements and/or Higher System reliability

29 29 Grazie Thanks 谢 谢