Mosfet driver

Thread Starter

vandaycalta

Joined Mar 22, 2016
53
Can anyone tell me if I can use a mosfet driver to drive a n channel mosfet with a microcontroller. I can not find one(mosfet) suitable for my needs that is also having a logic level gate. Can I use a mosfet driver to control the mosfet with a microcontroller such as an arduino?


Val
 

GopherT

Joined Nov 23, 2012
8,012
Can anyone tell me if I can use a mosfet driver to drive a n channel mosfet with a microcontroller. I can not find one(mosfet) suitable for my needs that is also having a logic level gate. Can I use a mosfet driver to control the mosfet with a microcontroller such as an arduino?


Val
Yes, a Microcontroller can send signal to the driver, the driver applies gate voltage to MOSFET.

Post driver and MOSFET that you plan to use.
 

Thread Starter

vandaycalta

Joined Mar 22, 2016
53
Yes, a Microcontroller can send signal to the driver, the driver applies gate voltage to MOSFET.

Post driver and MOSFET that you plan to use.
Thank you for your reply.
I am looking at a mosfet similar to this:FCB36N60NTM.
As for the driver for the mosfet, that is what I dont know on how I would choose one. I know that the microcontroller output will be 5v and 20mA max.

Val
 

tracecom

Joined Apr 16, 2010
3,944
Thank you for your reply.
I am looking at a mosfet similar to this:FCB36N60NTM.
As for the driver for the mosfet, that is what I dont know on how I would choose one. I know that the microcontroller output will be 5v and 20mA max.

Val
You will be able to drive that MOSFET directly from the uC. Connect an output from the uC to the gate of the MOSFET through an (optional) 330 ohm resistor. Use a pull down resistor (100k) from the gate to ground. Connect the source to ground and the drain to the load. A high output from the uC will turn the MOSFET on and switch ground to the load.
 

dannyf

Joined Sep 13, 2015
2,197
Yes, you can the driver doesn't know if it is driven by an arduino or a xrduino.

Voltage and peak current are two key specs, in addition to topology (high side, low side or half bridge, etc.) Puck your MOSFETs based on your load. Figure out its gate charge, and switching frequency. Then you have peak current. Give your self some room over that.
 

Thread Starter

vandaycalta

Joined Mar 22, 2016
53
Yes, you can the driver doesn't know if it is driven by an arduino or a xrduino.

Voltage and peak current are two key specs, in addition to topology (high side, low side or half bridge, etc.) Puck your MOSFETs based on your load. Figure out its gate charge, and switching frequency. Then you have peak current. Give your self some room over that.
Thanks for your reply.

Do I have to think about saturation with a mosfet and wanting to use it as a switch? Thats where I get confused as I dont want it in the active region.
Thanks for your help.

Val
 

tracecom

Joined Apr 16, 2010
3,944
I was unable to find a n channel mosfet that I could use w/ a logic level gate that was 600v and 36a. I want to switch this load up to 600 hz.
The MOSFET you linked to is logic level; it switches on at 4V or less. And if you read my previous post, it tells you how to switch the MOSFET on.
 

Thread Starter

vandaycalta

Joined Mar 22, 2016
53
The MOSFET you linked to is logic level; it switches on at 4V or less. And if you read my previous post, it tells you how to switch the MOSFET on.
I now see the Vgs threshold is 2v min and 4v max so a logic level of 5v will work with this mosfet. I also thank you for your additional information regarding the pull down resistor and the 330 gate resistor. Im trying to learn and also trying not to offend anyone at the same time.

Val
 

GopherT

Joined Nov 23, 2012
8,012
I now see the Vgs threshold is 2v min and 4v max so a logic level of 5v will work with this mosfet. I also thank you for your additional information regarding the pull down resistor and the 330 gate resistor. Im trying to learn and also trying not to offend anyone at the same time.

Val
Don't worry about offending anyone. Someone will always figure out a way to be offended but we all keep coming back. Just ask away.
 

Thread Starter

vandaycalta

Joined Mar 22, 2016
53
Don't worry about offending anyone. Someone will always figure out a way to be offended but we all keep coming back. Just ask away.
Thank you for your kind words. How can I tell on the data sheet if the mosfet I want to use will switch fast enough? Can you tell me what I would be looking for? I am looking to switch around 600hz.

Val
 

GopherT

Joined Nov 23, 2012
8,012
Thank you for your kind words. How can I tell on the data sheet if the mosfet I want to use will switch fast enough? Can you tell me what I would be looking for? I am looking to switch around 600hz.

Val
This is a high speed MOSFET and 600 Hz is easily achieved. The input capacitance (or input charge) is the key variable that determines speed of the mosfet. This one can handle 1000x what you need.

Are the pins on your Arduino output 5V? Or 3.3V? Or, when in the high state, something in between?

The MOSFET you selected does have threshold voltage of under 5 V but the graph is for a TYPICAL part out of a day's worth of manufacturing. Note that the datasheet only specifies on resistance at 10V gate-source voltage. I hope you get a part that saturates at 5V. The manufacturer dies not list this part as "logic level" Vgs. The Digikey site categorizes this part as Standard and not as Logic Level (e.g 10V).
 

Thread Starter

vandaycalta

Joined Mar 22, 2016
53
This is a high speed MOSFET and 600 Hz is easily achieved. The input capacitance (or input charge) is the key variable that determines speed of the mosfet. This one can handle 1000x what you need.

Are the pins on your Arduino output 5V? Or 3.3V? Or, when in the high state, something in between?

The MOSFET you selected does have threshold voltage of under 5 V but the graph is for a TYPICAL part out of a day's worth of manufacturing. Note that the datasheet only specifies on resistance at 10V gate-source voltage. I hope you get a part that saturates at 5V. The manufacturer dies not list this part as "logic level" Vgs. The Digikey site categorizes this part as Standard and not as Logic Level (e.g 10V).
I do see what you mean on the input capacitance. I also see that this part is listed as standard. So you are saying that this part may not act as a switch and have its threshold at 5v due to the fact that it is a mass produced part and the one tested for the data sheet had the specs as recorded? If this is the case would it be wiser or safer to use a mosfet driver with this mosfet?

Val
 

Thread Starter

vandaycalta

Joined Mar 22, 2016
53
This is a high speed MOSFET and 600 Hz is easily achieved. The input capacitance (or input charge) is the key variable that determines speed of the mosfet. This one can handle 1000x what you need.

Are the pins on your Arduino output 5V? Or 3.3V? Or, when in the high state, something in between?

The MOSFET you selected does have threshold voltage of under 5 V but the graph is for a TYPICAL part out of a day's worth of manufacturing. Note that the datasheet only specifies on resistance at 10V gate-source voltage. I hope you get a part that saturates at 5V. The manufacturer dies not list this part as "logic level" Vgs. The Digikey site categorizes this part as Standard and not as Logic Level (e.g 10V).
THe pins on my micro are 5v with a max current of 20ma.

Val
 

ronv

Joined Nov 12, 2008
3,770
THe pins on my micro are 5v with a max current of 20ma.

Val
What you have will probably work, but it is not ideal. At 5 volts the fet is not turned on as good as it would be at 10 or 12 volts.
With 15 or 20 ma of gate drive current it will switch kind of slow. To get an idea you can divide the Nc value by the gate current so 87Nc / .02 = 4.3 usec. This alsohe ats the fet up a bit since during this time it is kind of half on and half off. Not to bad at 600 Hz but if you decide to run it faster it will start to add up.
Tell us more about what you are driving with the fet.
 

shortbus

Joined Sep 30, 2009
7,348
You will be able to drive that MOSFET directly from the uC. Connect an output from the uC to the gate of the MOSFET through an (optional) 330 ohm resistor.
Isn't 330 ohm kind of high for a gate resistor? I would think 33ohm would be more like it, according to most Application notes on mosfets.
 

tracecom

Joined Apr 16, 2010
3,944
Isn't 330 ohm kind of high for a gate resistor? I would think 33ohm would be more like it, according to most Application notes on mosfets.
My thinking is that the resistor is there to protect the uC from the unlikely event of the MOSFET gate being shorted to ground. As I posted, the resistor is optional, and the truth is I often leave it out entirely.
 

tracecom

Joined Apr 16, 2010
3,944
Further to my previous post, I have always wondered why some schematics show a small (<100 Ohms) in the gate lead to a MOSFET. If there is a real need for it, I would be pleased to know what such a resistor is for (no sarcasm intended.) Thanks.
 
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