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DRV8301 nOCWT PIN

Markus Hoffet
Prodigy 220 points
Other Parts Discussed in Thread: DRV8301

Hello,

We are using a DRV8301 gate driver for a rectifier application. I observed that some of our FETs generate excessive heat because they don't switch good. I saw that the nOCWT PIN is changing his level all the time. See the attached screen print. I do nothing with SPI communicatio and I have no load connected. What can trigger the nOCWT PIN when nothing is running and nothing is set over SPI. What is the effect to the ouptuts when nOCWT is going low?

CH1 = INH_A, CH2 = INL_A, CH3 = nOCWT

Thanks for your reply, 

Markus

  • 0
    TI__Mastermind 26065 points
    Hi Markus,

    When you say FETs generate excessive heat, it is with load or not? if not, it means maybe there is shoot through issue of the high side and low side.

    What is nFAULT signal as well as the nOCWT?

    Several things need to check:

    PowerPAD is soldered well to the GND plane.
    The MOSFETs Qg should match with the gate driver current. What is your MOSFETs part number and Qg now?
    Is there any external components to the MOSFETs gate, better post your schemtic.

    Best regards,
  • 0 in reply to Wilson Zuo
    Prodigy 220 points
    Hello Wilson,

    Thanks for the quick reply.
    Yes the heat in the MOSFETs I see when I have the 3 phase generator as input source connected. But the signal on nOCWT looks like i posted when nothing is connected.
    nFAULT is always high. So no error reported on this PIN.

    The MOSFETs are infineon BSC042N03MSG
    e2e.ti.com/.../Driver.JPG
    e2e.ti.com/.../Rectifier.JPG

    Best Regards
    Markus