- This is my first time playing around with MOSFETs. I wanted to know how much continuous current could be handled by MOSFETs when they are controlled by Arduino IO. Also, I would like to know if heatsinks are necessary. The datasheets gave some indication, but I could not find the graphs I was looking for, so I made my own.
Materials
The following MOSFETs were compared:
- - FQP30N06L
- - IRLZ44N
- - IRF3205
The first two MOSFETs are "Logic Level" according to the datasheet and should be suitable for use with Arduino's.
Method
For every MOSFET the drop voltage (Vds) was measured at different currents (Id).
The resistance Rds(on) and the dissipated power Pd were then calculated.
The MOSFETs were without a heatsink and the current was increased until the dissipated power reached about 1 watt.
During this experiment it was determined at which currents these MOSFET were deemed "too hot to handle" by using a finger probe.
All this was done for a gate voltage (Vg) of 3.3 V and 4.5 V. The choice for 4.5 V (rather than 5V), was made because the working voltage of Arduino's is just above 4.6 V when powered from USB. The MOSFETs will perform better at 5V.
Results
In the graph below it can be seen that all three MOSFETs performed OK at a gate voltage of 4.5V. The IRLZ44N had the lowest resistance and the least power dissipated. The IRF3205 performed worst, but it still did a good job, especially considering it is not advertised as a logic level MOSFET.
New graphs in the post below....
The IRF3205 was deemed too hot to handle at a current of 4.1 A. (You can keep your finger on 3.6 A, but not on 4.1 A) The IRLZ44N and the FQP30N06L could go 0.5 A higher.
At a gate voltage of 3.3V, again the IRLZ44N performed best. Remarkably, the "logic level" FQP30N06L now performed worse than the IRF3205. A second FQP30N06L was tested but gave the same results.
New graphs in the post below....
The MOSFETs were too hot to handle at IRLZ44N: 4.1 A, IRF3205: 3.6 A and FQP30N06L: 2.6 A.
Conclusions
All three MOSFETs can be used without a heatsink for the currents tested.
The FQP30N06L performs the worst at 3.3V. It gets rather hot and the maximum continuous current is limited. It does much better at 5V.
The IRF3205 is not advertised as a logic level MOSFET, but still does a pretty good job.
The IRLZ44N performs best at both voltages.
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