resistances and capacitors in parallel with mosfet

chao yang

Hello

When I Design my own board，If I make resistances and capacitors be connected with the MOSFET in parallel (as shown below)，then whether this resistance and capacitor would affect Voltage Filter Pole or affect performance of motor parameter identifying ?

chao

over 9 years ago

0 Nicholas Oborny over 9 years ago

TI__Mastermind 21305 points

Chao,

I don't there will be any issues with the 10k Ohm as long as the gate driver has sufficient current to drive the additional current draw.

What is the reasoning for the capacitors? These capacitors are connected to the switching node which is going to cause high voltage spikes when the node switches as well as sending large energy through the capacitors. Snubbers are usually implemented with a series resistance and much smaller capacitance.

0 chao yang over 9 years ago in reply to Nicholas Oborny

Expert 1620 points

What is the reasoning for the capacitors?

I can't explain it clearly.Look at the Infineon manual，that is exactly what it did for high power：Infineon Application Note.pdf

0 Nicholas Oborny over 9 years ago in reply to chao yang

TI__Mastermind 21305 points

Chao,

I see no explanation in the app note for the capacitor divider and can't really comment furthur on the Infineon design.

0 chao yang over 9 years ago in reply to Nicholas Oborny

Expert 1620 points

Nick

If I design a RC snubber what you said,then whether the snubber would affect Voltage Filter Pole or affect input of FAST observer ?

chao

0 Nicholas Oborny over 9 years ago in reply to chao yang

TI__Mastermind 21305 points

RC snubbers are typically targeted at ringing frequencies > 1MHz. I cannot say for sure, but I think this would have minimal effect on the FAST feedback.

0 chao yang over 9 years ago in reply to Nicholas Oborny

Expert 1620 points

Thanks.
To be on the safe side,I will add nothing around mosfets except that 10K resistance.

chao

C2000™︎ microcontrollers

C2000 microcontrollers forum

resistances and capacitors in parallel with mosfet