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MOSFET (Si/SiC) Forum Discussions

User18098
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Dear Infineon Community,

I am very much interested in the 1.2kV/6mR EasyDual 2B SiC power module (FF6MR12W2M1_B11) and have a few short questions to the experienced user:


  • Do you know of a plug & play gate driver and/or reference design for a quick evaluation of a phase-leg or H-bridge in the laboratory supporting switching frequencies >>100 kHz?
  • From the IFX gate driver application note I learned that the 1EDI60H12AH EiceDriver is one of the recommended gate driver ICs. What is roughly the max. feasible switching frequency (soft-switching, ZVS) using this IC to implement a gate drive.
    Is up to 500 kHz switching frequency (~5 Watt of power delivered to the gate of the power module) possible considering some conventional means of cooling?
  • Do you think one can actually achieve 500 kHz switching frequency with the 1.2kV/6mR SiC power module in a resonance type converter (i.e. ZVS and comparably small turn-off currents).


I am very much looking forward to your answers and advice.

Kind Regards,
Dominik
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electricuwe
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Moderator 5 sign-ins 25 replies posted 10 solutions authored
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Dear Dominik,

in general the operation at several 100 kHz under ZVS condition is feasible with this module.

You have to do separate power loss and junction temperature calculations for the module as well as for the driver.

For the driver I have calculated a power demand of approx. 4 W. This power is dissipated within the internal gate resistance, the external gate resistance and the driver output impedance according to the ratios of resistance. With a total gate voltage swing of 20 V (I'd recommend -2 V and +18 V if you need no SC-rating) and recommended turn-on and turn-off gate resistors the peak gate current is approx. 9 A. The driver you mention would be marginally suitable from a peak current point of view, but for sure it is undersized under thermal aspects. Hence you should consider combining a lower current driver with an external booster. For the booster you should choose a solution with low thermal resistance to the PCB and cooling area on the PCB. Isolated gate driver ICs in general do not provide significant thermal dissipation capability as isolation requirements (clearance and creepage) and power dissipation enhancements (e.g. exposed die pad) are not compatible with each other.

Best regards,
electricuwe

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electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
Dear Dominik,

in general the operation at several 100 kHz under ZVS condition is feasible with this module.

You have to do separate power loss and junction temperature calculations for the module as well as for the driver.

For the driver I have calculated a power demand of approx. 4 W. This power is dissipated within the internal gate resistance, the external gate resistance and the driver output impedance according to the ratios of resistance. With a total gate voltage swing of 20 V (I'd recommend -2 V and +18 V if you need no SC-rating) and recommended turn-on and turn-off gate resistors the peak gate current is approx. 9 A. The driver you mention would be marginally suitable from a peak current point of view, but for sure it is undersized under thermal aspects. Hence you should consider combining a lower current driver with an external booster. For the booster you should choose a solution with low thermal resistance to the PCB and cooling area on the PCB. Isolated gate driver ICs in general do not provide significant thermal dissipation capability as isolation requirements (clearance and creepage) and power dissipation enhancements (e.g. exposed die pad) are not compatible with each other.

Best regards,
electricuwe
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User18098
Level 1
First question asked First reply posted
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Dear electricuwe,

thanks for your expert insight which is very much appreciated.
Using an external booster circuit is a very good idea! I did that once using a pair of (stacked) complementary PNP and NPN BJTs.
Would you also suggest so?

Best Regards,
Dominik
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electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
Dear Dominik,

yes, using complementary bipolar transistors in emitter follower configuration is one option. Look for types with specified current gain at high current and high transit frequency. Zetex, now Diodes, has a lot of suitable types. ZXTN2010ZTA and ZXTP2012ZTA or ZXGD3006E6 (both trasnsistors within the same package and specified as gate driver) we use on many on our Evaluation boards. Dedicated non-isolated gate drivers from IXYS (IX??6??) are an alternate choice. Many other Mosfet gate drivers do not provide sufficient supply voltage range.

Best regards,
electricuwe
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