Calculation of gate resistor wattage

[Mr.Cool]

Pv = Vg²*Cg*f (assuming unipolar gate drive and constant Cg). Interestingly it's independent of gate resistance.

aye, interesting.. and even more interesting is to think .. the resistor does not get a say in the equation but it takes practically ALL of the power dissipation! ha.

those pulse rating curves i understood them to be single pulse event with sufficient cool down period after.. while in a gate driver application it is continuous pulsing. so i thought those curves could not be used to determine resistor survivability. am i wrong?

 

[FvM]

those pulse rating curves i understood them to be single pulse event with sufficient cool down period after.. while in a gate driver application it is continuous pulsing. so i thought those curves could not be used to determine resistor survivability. am i wrong?

Both curves are for continuous pulsing, there are additional single pulse charts in the respective (Vishay) datasheets. The shown curves are missing a duty cycle specification, but for the small duty cyles under discussion they should fit anyway.

 

[deepakchikane]

Hi deepakchikan
It is simple .
You know about Tr of your mosfet . ( rise time ) ( by datasheet )
Vc=1/C integral over ic dt ====> from zero up to tr ====> Vc=tr*ic/c ===> ic = Vc*c/tr for usual mosfets VGS=15 it will be turned on . so Vc=15 then required ic = 15*ciss/tr and of course it is inrush current . so required power of the series resistor with gate can be calculated according to this inrush current .
Best Wishes
Goldsmith

Hello Goldsmith..

how to calculate the required current for the particular mosfets..

1) will there be total gate charge (drain-gate capacitance + gate to sorce capacitance)..??

2)some peoples are just telling that only ciss is necesaary.. will it be ok..

according to physics,
i=Q/T
Q Tends to total gate charge (then both cap should be there)
T=Tends to time required to charge above capacitance..

so equation will be i=total gate charge (Drain to Gate cap+Gate to Source cap)/Rising time

will above equation leads to right gate triggering of mosfets..??

smwot confused.. help needed.. Else mention some links of detailing
looking forward to hearing you soon..!!
Deepak C

*Trying to explore something in the Electronic Fields..Because i am just believing science not divine..!!