DRV8308: MOSFET burn

Peter Mirtschink

Part Number: DRV8308

Hey,

we use the DRV8308 with IRFS7430 with 50kHz and 100mA Drive current. But of we work with lower PWM duty cycle the Highside Mosfet burn. Seems to be an thermal problem. What could we try to avoid this Problem?

Regards Peter

over 2 years ago

0 Aaron Barrera over 2 years ago

TI__Mastermind 26046 points

Hi Peter,

IRF7430 has very large Qgd of 209nC. Using 100mA drive current results in VDS slew rate of around 2.09ms. This long turn on time causes increases in thermal dissipation due to Ids^2 * Rdson power losses as thermal heat from MOSFET package.

Can you increase the gate drive current IDRIVE to max setting? If MOSFET continues to burn, you need to use lower Qgd MOSFET so VDS slew rate is around 100-500ns.

Find more info on calculation of IDRIVE here: https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/38/t/796378

Thanks,
Aaron

0 Peter Mirtschink over 2 years ago in reply to Aaron Barrera

Prodigy 220 points

Hi Aaron,

thank you, I have tried the CSD18511 MOSFET from TI and seems to work good. Because the Layout is for D2PAK 7 I can not use this MOSFET. What did you thing about IPB020N04 G from Infineon?

About the Qgd of the IRF7430, from where you took 209nC? I only find 98 nC in the data sheet?

Regards,

Peter

0 Aaron Barrera over 2 years ago in reply to Peter Mirtschink

TI__Mastermind 26046 points

Hi Peter,

Can you please send the link of the MOSFET datasheet used? I looked at wrong device, it appears to be IRF743, but cannot find good documentation.

If you're using the 3-pin through hole leaded MOSFET package, can you use IRF740? https://www.vishay.com/docs/91054/91054.pdf
Qgd appears to be 32nC which will help increase VDS slew rate.

Thanks,
Aaron

0 Peter Mirtschink over 2 years ago in reply to Aaron Barrera

Prodigy 220 points

Hi Aaron,

the PDF of the used MOSFET:

https://www.infineon.com/dgdl/Infineon-IRFS7430-DS-v01_00-EN.pdf?fileId=5546d462576f3475015792dbfbd6000d

and here the CDS18511KTT from my test today without problems:

https://www.ti.com/lit/ds/symlink/csd18511ktt.pdf?ts=1639402400273&ref_url=https%253A%252F%252Fwww.google.com%252F

Because we have changed the package to D2PAK-7 I would use this one. What did you mean about this:

https://www.infineon.com/dgdl/Infineon-IPB020N04N-DS-v01_03-en.pdf?fileId=db3a30431936bc4b0119382c70a859ed

We used D2PAK and changed in past to D2PAK-7. Maybe I will change back to D2PAK and CSD18511KT but for now I need an solution. Can I use the IPB020N02N G? We have 18V System and maximum 100A.

Regards Peter

0 Aaron Barrera over 2 years ago in reply to Peter Mirtschink

TI__Mastermind 26046 points

Hi Peter,

The IPB020N02N G looks like a good solution. It has low Qgd = 11nC (TI FET uses 9nC, so both are low). Original FET has 10x higher Qgd = 98nC, therefore turn-on is 10x slower and had higher Rdson switching losses and likely overheated.

Thanks,
Aaron

0 Peter Mirtschink over 2 years ago in reply to Aaron Barrera

Prodigy 220 points

Thanks Aaron,

we will change this an will see if all work fine.

0 Aaron Barrera over 2 years ago in reply to Peter Mirtschink

TI__Mastermind 26046 points

Sure thing, I will close this thread. Feel free to reply or start a new one if this did not resolve your issue.

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DRV8308: MOSFET burn