For MOSFET operation, the switching time (rise and fall time) of MOSFET varies depending on the resistor of the connected gate.
When the switching time is short or long, the following problems may occur. Please set the switching time suitable for the system.
- If the resistance of the gate is small,
Switching time is reduced and ringing (damped oscillation) may occur.
Ringing may result in oscillations or EMI noises.
- If the resistance of the gate is large,
Switching time becomes longer, switching loss increases, and more heat is generated.
In the bridge circuit, a short circuit may occur across the upper and lower MOSFETs by combination of the gate resistances.
Therefore, it is necessary to consider the optimum gate resistance.
For details on how to suppress parasitic oscillations in MOSFET parallel operation, see what are the considerations when using MOSFETs in parallel?
What are the considerations when using MOSFETs in parallel?