Logic-Level MOSFET (5v Gate); drive from 3.3v MC with level shifter? BJT? separate driver chip.

Thread Starter

patrickstefanski

Joined Apr 15, 2017
36
Hi, I need some guidance on how to drive my MOSFET properly.
This is the MOSFET in question: BUK962R5-60E DATASHEET
The MOSFET is acting as a switch for 12V @ 20A max. (more likely 5A nominal) from battery to motor.

Here is the schematic

Elsewhere in the schematic is a 5V step down so I have 5v available to me.

My Micro-controller is 3.3v. I'm wondering what component I need to put in place between the the arduino pins (I have two pins running in parallel as recommended by a user to flood the gate better, though this may become irrelevant with a component between them) and the Gate.

Options:
-I've read about using a level shifter to shift voltage from 3.3v to 5v. (Is 5v definitely enough? looks like it from the datasheet, but I'm not an expert).
-Also i can use a BJT as a 5v switch to the Gate?
-Or I've heard people talking about dedicated MOSFET driver ICs. I did a cursory search of digikey but not sure what values I would need or what chip would work best for this setup.

Any reason why any of those options would be better/worse than another? Suggestions?
Any input would be really helpful. Thanks!
 

Thread Starter

patrickstefanski

Joined Apr 15, 2017
36
Ah yes! thank you this is exactly what I was looking for.

I suppose this would be equally useful to power the 5v logic of neopixles in the same way?
 

ArakelTheDragon

Joined Nov 18, 2016
1,264
The level shifter normally contains a CMOS inside of it. You can easily change your MOS with a 3.3V activated one. You can also see the circuit in the "pololu level shifter".
 

jpanhalt

Joined Jan 18, 2008
8,102
Are you sure you need to level shift? That mosfet is close to being fully on at 3.3V (Vgs). Guessing RDS(on) = 2.5 mohm at 3.3V and 2.0 mohm at 5.0V, the difference in heat (watt) is 1W versus 0.8W at 20A (I^2*R), respectively.
 

Thread Starter

patrickstefanski

Joined Apr 15, 2017
36
Are you sure you need to level shift? That mosfet is close to being fully on at 3.3V (Vgs). Guessing RDS(on) = 2.5 mohm at 3.3V and 2.0 mohm at 5.0V, the difference in heat (watt) is 1W versus 0.8W at 20A (I^2*R), respectively.
I tried it without the level shift and it wasn't responsive.
It could have been a separate issue, but I tried again with the level shift and it worked.
There were other changes which could be leading to this, so maybe let me try my exact setup again wihtout the level shift.
 

ScottWang

Joined Aug 23, 2012
6,834
According to the spec when you connect the 3.3V to the Vgs of MOSFET, it should works, unless the spec was wrong, please to see the fig. 7 (page 6) and fig. 10 (page 7).
 
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