I have problem when I send high signal from arduino it not open source and drain.

Why is it?

Here is datasheet: http://pdf.datasheetcatalog.com/datasheet/fairchild/IRF630B.pdf

I found Gate-Source Voltage: ± 30 is that mean I must send 30VDC to open conection between source and drain?


2 Answers 2


This part should be driven with about 10V to get the minimum guaranteed 'on' resistance. The relevant section is below:

enter image description here

At as much as 4V (the line above) the MOSFET may only be conducting 250uA, so hardly on at all.

"Typically" it will turn on fairly well with a 5V input, but with 3.3V it may conduct very little current. There is no guarantee your particular part is typical, but if you are actually driving it with 5V there may be something else wrong.

+/-30V is the absolute maximum gate to source voltage. You should not get anywhere near that voltage. Above that, destruction can occur, and there is hardly any gain to be had from more than 10V-15V drive.

  • \$\begingroup\$ Thanks for answer. Is there any way to simple test MOSFET with arduino? \$\endgroup\$ Commented Jan 15, 2016 at 19:35
  • \$\begingroup\$ You are right it was problem with my MOSFET. \$\endgroup\$ Commented Jan 15, 2016 at 22:20

If you have a LED then this is an easy way to test the mosfet:

enter image description here

Or this is even simpler, because it doesnt even use the Arduino:

enter image description here

One thing to remember is that the gate voltage should not just be 5V, but instead it must have 5 volts HIGHER than the source. So if the source is connected to ground (zero volts) then the mosfet will allow current throgh it when the voltage at the gate gets high enough. The drain voltage should also be higher than the source voltage because current should go in to drain and out of source.

What I mean is that if the source is connected to for example 5V then the voltage at the gate would need to be around 10V or something like that. And by the way, an unconnected pin is not the same thing as 0V.

  • 1
    \$\begingroup\$ Good answer. Are you aware that there's an online schematic editor? Button is in the editor toolbar. \$\endgroup\$
    – Transistor
    Commented Jan 15, 2016 at 20:46
  • \$\begingroup\$ Oops. No I did not know that. Now I do. Thanks. \$\endgroup\$ Commented Jan 15, 2016 at 20:49

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