Hello
I'm using arduino mega and, I have to control pwm signal with this arduino.
But that signal have to 12V so, I decide to use mosfet transistor to control 12V.
Cause arduino's outpin voltage is only 5V.
So I buy 12V 5A adapter.
And I collect irf520 transistor.
Does it work in this situation?
Not likely. Look at the datasheet. The second line says Vgs = 10V. This is not a logic level (5V) device. Arduino cannot put out the 10 volts required to turn the device on fully.
What is the device?
Can you tell us how much current you need to switch with your MOSFET?
If you need to create 12V PWM waveform, you do need a 12V power supply but you do not need an IRF520, use an IRL520 logic MOSFET.
What are you driving that you need 12V PWM waveform?
The IRF520 is not logic level, is 100V rated (and thus has a very high on-resistance, this is why you don't
use 100V devices for 12V circuits)
You need a logic level MOSFET, rated at 30V or 40V, with a nice low on resistance so it doesn't need
a heat sink. If 5A is the current level involved, use a device with 15 milliohms on resistance or less
if possible.
What frequency PWM? If a high frequency you'll need a MOSFET driver chip anyway, in which case the
MOSFET can be non-logic level.
well...
I seen irfz44n that can controlled by arduino pwm.
cause it is cheaper than IRL520 and does it all right?
My purpose is to control irf1405 that can't controlled by arduino
So I use 12V adapter and, irfz44n to provide adaptable gate voltage.
And, have to control 30 number of irf1405 with one adapter and 30 irfz44n to devise parallel circuit.
So, does there a proper current for 12v adapter?
Hi,
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
As this is getting very complicated.
What is your project?
Thanks.. Tom.. 
dongjee33:
well...
I seen irfz44n that can controlled by arduino pwm.
cause it is cheaper than IRL520 and does it all right?My purpose is to control irf1405 that can't controlled by arduino
So I use 12V adapter and, irfz44n to provide adaptable gate voltage.
And, have to control 30 number of irf1405 with one adapter and 30 irfz44n to devise parallel circuit.
So, does there a proper current for 12v adapter?
The IRFZ44N is not logic level.
If you want to drive an IRF1405, use a gate driver chip? That's what they are for.
But, just using low current, doesn't it okay to drive irfz44n?
less then 1A, maybe it's heat doesn't go up. I think
And seeing Typical Transfer Characteristics, doesn't 1A get in safe area?
And I will connect it in parallel so maybe it will be almost 40ma.
If your transistor is saturated, should be okay. Vds = ~0v