hi expert
when I use UCC21737-Q1 to driver SiC. According to the following information from <SLUUBX2B.pdf>. I remove a 20np capacitor in my own PCB.
BUT SiC supplier advice to add this 20np capacitor.
Pls share your valuable comments.
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hi expert
when I use UCC21737-Q1 to driver SiC. According to the following information from <SLUUBX2B.pdf>. I remove a 20np capacitor in my own PCB.
BUT SiC supplier advice to add this 20np capacitor.
Pls share your valuable comments.
Hi, Jay,
C26 is a simulated load for evaluation purposes. It is intended to provide a load for the driver when no power device is connected.
A small capacitor, like you have, is fine, and can help ringing on the gate.
Let us know if you have further questions, Jay.
Best regards,
Don
hi Don
whether can i think that R and C of gate both can affect ringing on the gate.
we can use large R or/and large C of gate to reduce EMI.
what is different between the two ways?
thanks.
Hi Jay,
As the timeconstant is RC, so R and C both directly proportional to rise time of the Gate voltage. But its not jsut the external Gate and external capacitance in the system, you need to consider all the R [Rint of the driver, R gate external, Rint of the FET] and C [Ciss of the FET+ external cap] of the system.
In case of higher R, we are limiting the current - but with higher C, it takes more time to charge to the required voltage.
It will be good to balance RC based on the FET's recommendation.
Here is a technote about how to choose the optimum external gate resistance.
Hope it helps.
Please press "Resolved" button if it answers your question.
Thanks
Sasi