Mosfet driver simple question

[ikalogic]

Hi!

Driving 350W, 15A loads have never been my cup of tea, yet i have to dig into that for work.


I am using this mosfet driver:
https://www.electro-tech-online.com/custompdfs/2013/04/77752.pdf

to drive n channel IGBTs.

I am really curious about one thing, the datasheet talks about 2 and 3 A currents for the Top and Botom Gates control. Huh!!?? why so much current? i though no current was flowing ? Or is this just needed to very quickly charge/discharge the mosfet's gate?

I am using a buck power supply to provide the VCC for the driver, it can supply 2Amps continuous. I assume this is enough since - as far as i understand - the 2 / 3 Amps used to drive the mosfets is just a surge, right?

am i missing something here?

Thanks a lot for sharing your experience

 

[jpanhalt]

Those gate currents are output ratings, not continuous ratings. It is for a short duration. It is as if you charged a capacitor with your supply, and then discharged it rapidly.

As for the mosfet itself, the high current charges the gate capacitance to turn it on rapidly. There is no continuous gate current for the mosfet itself. (If you have a gate drain resistor, then of course, there can be continuous current.)

John

 

[ikalogic]

Thanks.. that confirms my thought

 

[crutschow]

If you look at the gate charge value in the spec sheet for the MOSFET you can determine how much average current is required to drive it. It's approximately f*Q, where f is the frequency and Q is the gate charge.