# Logic level mosfet wont drive solenoid

I am trying to find out why my current mosfet is not working by looking over the datasheet. Ultimately I am just trying to buy a mosfet that I know will work, but I want to understand the datasheets fully before purchasing. I am trying to drive a solenoid with a microcontroller and using the mosfet as a switch. The MC outputs 3.3 volts, and the solenoid is a 12V, 2 amp. Direct current. The mosfet is an RFP30N06LE. The MC goes high for 500ms then off. I have my circuit wired as below (ironically, this random picture even has the same mosfet as me)

I understand that a solenoid will require a flyback diode that is not shown. I do not currently have one, but I dont think that is the problem. In the datasheet here are the values I understand to be important to follow when sizing a mosfet.

Looking at the above data, it appears you need to apply a minimum of 1 volt to get the mosfet to begin opening. By 5 volts, the mosfet is fully open. I am applying 3.3 volts, so the mosfet is not fully open. However, according to the graph, a voltage of 3.3 to the gate allows for about 20 amps (albeit at 15 volts, not 12), which is more than my required 2. When I tried this in real life, I did not get a reaction from the solenoid at 3.3 volts. I then used an arduino 5 volt output to try and trigger the solenoid. Still nothing, but the mosfet got very hot. Finally, I applied 12 volts to the mosfet gate (above the MFG 10 volt maximum) and the solenoid opened.

What am i missing? Since this mosfet doesn't work, I want to get the Nexperia PMV28UNEA instead. It has a VGS of 0.45V - 1V (smaller), and an RDSon of 3.9 amps at 2.5V (I need 2 amps at 3.3V). I want to make sure I understand things before I buy it though.

• Your belief that you don't need the diode is severely mistaken, as without it you are likely to permanently damage the MOSFET if you have not done so already - a probability strongly suggested by the MOSFET getting hot. As for debugging, get out your meter. What voltage do you measure gate to source? What do you measure drain to source? What do your measure across the coil of the solenoid? Edit these facts into the question itself. – Chris Stratton Dec 4 '20 at 17:33
• I then used an arduino 5 volt output to try and trigger the solenoid. Still nothing, but the mosfet got very hot. This means that the MOSFET tried to get turned on but unfortunately it couldn't decrease its DS resistance. Since the DS resistance remained high and a non-zero current flew through, the I²R dissipation thus the heat was high. Finally, I applied 12 volts to the mosfet gate (above the MFG 10 volt maximum) and the solenoid opened. Probably the MOSFET is nearly dead because of the lack of a flyback (a.k.a. freewheeling) diode. Sorry for your loss. – Rohat Kılıç Dec 4 '20 at 17:38
• The flyback diode is shown and it is needed and your MOSFET is now broken. – Andy aka Dec 4 '20 at 17:50
• Could you add a picture of your setup? – John Birckhead Dec 4 '20 at 19:51
• When you apply the 5 volts from your Arduino supply, measure the voltage between the source and the gate directly to make sure your grounds are good. – John Birckhead Dec 4 '20 at 20:10