Gate resistors in two switch forward

[Velkarn]

Hello, all!

two switch forward converter 90-260VAC in, 24V, 8A out.
i am driving mosfets with IR2113 driver, shematic from IR appnote.
please advice, how to select the value of gate resistors? is there a need to make circuit with diode (for fast discharge of gate capacitance)?

 

[KlausST]

Hi,

It depends on many parameters.
Transistor values
Switching frequency
Dead time
Pcb layout
Schematic
Driver values.

The resistor prevents ringing by decreasing output voltage rise rate.
A low impedance power path of the fet's source, a low coss of the fet, a low capacitive load path could also decrease ringing.
And the connection from fet source to driver should be low impedance and additionall should not carry the power current... individual routing of driver and power path...

Klaus

 

[Orson Cart]

start with 15 ohms on each fet, and a back diode across each (1A 40V schottky) this will get you going....