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MOSFET (Si/SiC) Forum Discussions

KUOWENYUNG
Level 3
50 sign-ins 10 replies posted 5 replies posted
Level 3

Dear Sir,

Infineon CFD7 has better performance for diode reverse voltage, but I have a problem and need your help.

1.Are the test conditions independent of dIF/dt and dV/dt? Because I seen STMicro DM2 devices tested at 900A/us.

2.How to distinguish diode or MOSFET dv/dt fault through Table8 circuit? Because I seen IFX MOSFET dv/dt specs > diode dv/dt, but both STMicro and TOSHIBA specs are the same.

3.Is Rg1 of table8 adjusted dv/dt, and inductance adjusted dIF/dt?

KUOWENYUNG_0-1652230461055.png

 

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1 Solution
Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @KUOWENYUNG ,

Typical diode reverse recovery characteristics will be as shown below. 

Meghana_0-1652946961879.png

di/dt and dv/dt indicated in above characteristics is measured using the test circuit shown in table 8. 

To understand more about diode reverse recovery characteristics, you may refer below app note. 

https://www.infineon.com/dgdl/an-989.pdf?fileId=5546d462533600a40153559fa625124d

Regards

Meghana R

 

 

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Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @KUOWENYUNG ,

Thank you for posting on Infineon developer community. 

1. Diode reverse voltage dv/dt will be dependent on the junction capacitance and the test circuit conditions and do not depend on the di/dt directly. Hence you may find independent values of maximum di/dt and dv/dt  for a given a test condition.

2. the dv/dt limits for both diode and MOSFETs are individually derived and they may vary based on the wafer. In the circuit shown in table-8 , dv/dt of diode and MOSFET is measured on different devices. To measure dv/dt of diode, MOSFET is permanently switched off as in low side switch shown in the test circuit. 

3. Yes. Rg1 regulates the dv/dt and inductor regulates the di/dt. 

Hope this helps. 

Regards,

Meghana R

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KUOWENYUNG
Level 3
50 sign-ins 10 replies posted 5 replies posted
Level 3

Dear Sir,

thank you for explanation! May I know where to find the diode junction capacitance value in the datasheet ?

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Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @KUOWENYUNG ,

Junction capacitance data may not have been provided in every part datasheet. Can you please let me know which device you are using and what is the purpose of this evaluation?

Regards

Meghana R

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KUOWENYUNG
Level 3
50 sign-ins 10 replies posted 5 replies posted
Level 3

Dear Sir,

Maybe I just want to understand the diode reverse dv/dt and di/dt change though the junction capacitance value you mentioned, because I still can't understand how to use get this specification though table 8.

thanks!

Kuo

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Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @KUOWENYUNG ,

Typical diode reverse recovery characteristics will be as shown below. 

Meghana_0-1652946961879.png

di/dt and dv/dt indicated in above characteristics is measured using the test circuit shown in table 8. 

To understand more about diode reverse recovery characteristics, you may refer below app note. 

https://www.infineon.com/dgdl/an-989.pdf?fileId=5546d462533600a40153559fa625124d

Regards

Meghana R

 

 

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