Switching to Higher Current w/ MOSFET


Thread Starter


I currently have a W9NK90Z with a 30VGS breakdown voltage. Right now, I'm not looking to buy a whole new MOSFET with a higher VGS breakdown.

I have the source connected to the ground and the drain connected to a 2nF capacitor in parallel with a 4.418uH primary of an air-core transformer. I really don’t want to lower the inductance by too much because it could lower the coupling coefficient? Right?

The series resistance is minimal. At the other end of the capacitor and inductor is a voltage source high enough to keep the MOSFET saturated when turned on.


The W9NK90Z has an Rds ON of 1.1 ohms. Based on that and the infrmation above, I'm going to guess the supply voltage is only about 7 volts. Am I correct in thinking that?
The Schematic

No one would run 30 volts on a MOSFET gate. Looking at the datasheet shows 10 volts being enough to turn this device on hard.
The MOSFET is turned on by a <30V pulse at the gate to make sure I don't exceed the VGS breakdown voltage. The problem was that when I turn it on with a 30V pulse in a simulator, the current switched by the MOSFET is only 6.59 amps.

I'm moving forward now.