Gate resistors in MOSFET

[jbc]

Hi everyone,

what is the functionality of the 4,7ohm resistors in the gate of mosfets exactly?

Thank you
regards

[ThierryGTLTS]

1. To limit the driver current.

2. To improve switching and stability, less ringing.

So it's very important.

Have a Nice Day.

Thierry

[pf26]

When you want to control the MOSFET turn ON and OFF times, the gate resistor limit the gate currents and increase MOSFET switching times.
Otherwise, the dV/dt would be higher, would generate larger RF emissions, and could be destructive (because of components and pcb parasitic inductance and capacitances, playing unexpected role at higher frequencies).
So you need to find a compromise between higher efficiency (requiring low switching times) and safety (especially that turning ON the low side FET never makes the high side also turn on due to some coupling).

[jbc]

Now it is clear.

Thank you very much
regards