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# I am still new to Mosfets.

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#### Lightium

##### Active Member
Can an IRFP250N handle 3 amps on its gate?

FET's are voltage controlled devices, they don't take any gate current (of any consequence). Why are you asking about gate current?.

Because in my simulation, the last thing to worry about that I measured was the gate current. I saw that it was about 3.5 amps and that worried me. Still though i am only dissipating about 20 watts.

Thank you.

Because in my simulation, the last thing to worry about that I measured was the gate current. I saw that it was about 3.5 amps
Obviously some sort of simulation error.

There are large gate currents if you are driving them with fast Tr and Tf
inputs, due to gate C.

Classic C equation :

Q = C x V
dQ/dT = I = C x dV/dT

Calculations for driving MOSFETs -

https://toshiba.semicon-storage.com/info/docget.jsp?did=59460

http://www.ti.com/lit/slua618

https://www.infineon.com/dgdl/an-937.pdf?fileId=5546d462533600a40153559ea1481181

An example :

Regards, Dana.

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for an estimated Ciss of 2500 pF, Rg=4 ohms est. Vgs=12 to get 3.5 Apeak the dV/dt=Vgs/RgC = 12/4*2.5e-9 or 12V/10ns. Then yes it is possible or a period of 10ns.

Because in my simulation, the last thing to worry about that I measured was the gate current. I saw that it was about 3.5 amps and that worried me. Still though i am only dissipating about 20 watts.
This is an AC current, not a DC current. The gate of a MOSFET is insulted from the other nodes by a layer of silicon dioxide, which is an insulator. Too much voltage would however be a bad-bad thing. The main reason for it is to charge and discharge the gate rapidly.

In a simulation, you can easily get 3.5 Amps (or more) into the gate of a mosfet for a few microseconds.

But is you have that much current continuously, then something is wrong.

In a simulation, you can easily get 3.5 Amps (or more) into the gate of a mosfet for a few microseconds.

But is you have that much current continuously, then something is wrong.
Another good thing to know, thank you.

In a simulation, you can easily get 3.5 Amps (or more) into the gate of a mosfet for a few microseconds.

But is you have that much current continuously, then something is wrong.
how do you get microseconds of gate current from Ic=CdV/dt using the parameters in #7 and Lightium ,what time constant did you get?

how do you get microseconds of gate current from Ic=CdV/dt using the parameters in #7 and Lightium ,what time constant did you get?
I didn't. The last post that was up when I started my reply was #5. If I had seen your post I wouldn't have replied at all.

My use of 'a few microseconds' was only intended to convey the concept of a very short time.

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