Driving multiple n-channel mosfets with a single npn transistor

Here is the deal,

I have some FQP20N60 mosfets that have a Vgs(th) of 5V. The Arduino isn't able to open them all the way and Im trying to drive a pretty big load, so I keep cooking them. I am attempting to use an TIP120 transistor to drive the mosfets with an alternate power source of 7 V to make sure they are fully open. I am having a hard time visualizing how to do this, and of course, I'm trying to take precautions as my main load and power source are larger than I have ever used. Here is a picture of what I am thinking.

Your circuit is very interesting, but is that interest worth the many cooked transistors? Remember that the MOSFETs only start conducting at Vgs(th), but need more voltage for noticeable current flow.

I'd use one or more logic level MOSFETs instead.

What is V2 ?

Why are you keying the 58 GND to the Arduino GND.

You need 10V (Vgs) to turn on that MOSFET.


Check your diagram. You're trying to drive the sources.

Q1 emitter goes to all sources, collector goes to all gates.
Gates go with a single resistor to a 12volt supply.
The single collector resistor should be a low enough value for fast 'on' switching of the fets.
Maybe not more than 220 ohm (1watt).
R9 must be able to provide enough base current to saturate the drive transistor (otherwise it will smoke too).
Maybe also 220 ohm (0,25watt).

You should of course use a dedicated gate drive chip for this kind of circuit.

Why are you keying the 58 GND to the Arduino GND.

It does appear strange but it works because the load current from the 58V circuit returns to the Q1 collector which is connected to the MOSFET drains, not to ground. Never try to ground the negative battery terminal, though...

Also 3 of the 4 resistors R1-R4 are redundant, as all the gates are tied together.

I'm not sure what V2 is. But I guess I would use a PNP transistor to feed whatever V2 is to the gates to turn them on, and use the NPN to drive the PNP. That's assuming V2 is higher than the Arduino's 5V. See attached.

I'm not sure what V2 is...

Time to install and play with the LTspice simulator.
V2 is a second voltage source. The first one is the 5volt Arduino pin.

I believe what you are after is this, where Arduino drives an NPN to sink gate current from a higher voltage supplied part to source higher voltage to the end device so that it can fully turn on when 5V from Arduino is insufficient.

Alternately, using an N-channel with a low Rds and 4.5V gate voltage would simplify things and Arduino can drive the gate directly with resistor to limit current into the gate capacitance.
AOD508, AOD516 for example.

Dunno where my responce has gone, here again:

The circuit is okay in general. The R1-R4 are in parallel, can be replaced by one. The voltage on these resistors is the GS voltage, controlled by Q1. This Darlington can be replaced by a universal low power npn.

Something is seriously wrong with the load. How can a 20A MOSFET drive 60V/1.3 Ohm ~ 45A?
Also V2 must be high enough to drive the FETs into saturation.