carrotSnack
Member
I've been trying to switch this n-channel mosfet to switch a transformer powered by a 24v battery at 5kHz. As nothing was happening I removed the transformer and looked just at the mosfet with an oscilloscope and saw it was constantly on. I tried an npn instead and it worked fine (I want to use the mosfet though for it's faster switching and higher current rating).
I took the frequency down to 100Hz for a better look.
This is the 5v square wave I'm using:
**broken link removed**
This is switching the 24v battery with the npn:
**broken link removed**
And this is the same with the mosfet:
**broken link removed**
It takes about 5ms to fall from 24.6v to 0v so it's no surprise at gave me a constant 24.6v at 5kHz. The datasheet though says it has a typical fall time of 355ns.
I tried using a different mosfet I had and the fall time was only a little bit less, still not enough for 5kHz.
I'm still learning so have I somehow damaged the mosfet or am I not using it correctly?
I took the frequency down to 100Hz for a better look.
This is the 5v square wave I'm using:
**broken link removed**
This is switching the 24v battery with the npn:
**broken link removed**
And this is the same with the mosfet:
**broken link removed**
It takes about 5ms to fall from 24.6v to 0v so it's no surprise at gave me a constant 24.6v at 5kHz. The datasheet though says it has a typical fall time of 355ns.
I tried using a different mosfet I had and the fall time was only a little bit less, still not enough for 5kHz.
I'm still learning so have I somehow damaged the mosfet or am I not using it correctly?
Last edited: