MOSFET Help needed

Thread Starter


Joined Jan 17, 2016
Hey All,
I have question in mosfet driving.
If mosfet gate voltage is 5V and Drain voltage is 3.3V. will mosfet work for this condition.
Simulation shows it works.

Thread Starter


Joined Jan 17, 2016
Yes, provided that the gate-to-source voltage is sufficient to handle the drain current.
Hey Dic,
Thanks for your reply but i am not fully aligned with your answer.
Per my knowledge VDS> (VGS-Vt).
Looking for more comments and thought here.


Joined Apr 4, 2016
The Drain - Source voltage (VDS) can be lower than the Gate - Source voltage (VGS). In fact this is normal when the device is switched on.
Your circuit will work provided the Gate - Source voltage is above the threshold and high enough to allow the device to conduct the required Drain - Source current. See the device datasheet for a graph of Output Characteristics.
For example, in the graph attached, to conduct a drain current of 0.4A, the Vgs needs to be greater than 5V. Increasing the Vgs will reduce the resistance (and hence the voltage drop) at that current.



Joined Feb 24, 2006
Field Effect Transistor means that the device operates because it establishes an electric field between the gate and the channel. The established field enhances the conductivity of the channel. When the transistor is "ON",(Vgs >> Vgs(th)), the drain, and the source are effectively at the same potential so there can be no such condition on Vds. You need to get your head out of the darkness.

Audioguru again

Joined Oct 21, 2019
The threshold voltage of Vgs is when the Mosfet is almost turned off, don't you want it turned on?
With your supply of 3.3V and a 2k load then the maximum current is only 1.65mA (0.00165A) so the Mosfet has barely any current.


Joined Mar 14, 2008
That's for operation in the saturation (active) region, not for operation as a switch (in the MOSFET linear region), which the OP is trying to do.
Unfortunately saturation has a different meaning for MOSFETs as compared to BJTs, as it does not mean fully on for a MOSFET (the one's that assigned the transistor operating point definitions apparently wanted to confuse the rest of us).

Thread Starter


Joined Jan 17, 2016
Hi All,
Thanks for valuable comments.
So take away from all comments for me is.
Mosfet will work.
I want mosfet to work as a switch and with very few drain current .


Joined Aug 7, 2020
If your drain current is 100uA (typical pullup current of a microcontroller) why are you using a 30Amp MOSFET?
You will have to supply some serious current into the gate if you want it to switch quickly!