I want to drive with PWM a load of 0.4 Amps (3.3V) using possibly 1 N-Channel Mosfet. I searched in all the internet (even in this forum) the right solution, and for my purpose I found that "common drain amplifier" configuration or "high switch" configuration can give me what i need.
I have available N-channel Mosfets, a power supply (variable voltage 3-12V) which can supply 2.25 Amps, the load and a bunch of resistors.
I tried to use first an IRF510 then I switched to logic level mosfet IRL530.
My first problem is that I can't reach the right current on my load (I reached that only when the Mosfet starts to burn).
I tried various polarization configuration but I'm still stuck.
The second problem is that my Arduino, when powered with 5V gives a peak of only 4.3V in the pwm pin, while powered with 7.5V I reach a peak of 5V and the same with a higher supply voltage. At this Voltages my mosfet doesn't fully open while Arduino starts to heat up if I use 9V for too long (with 9V I'm able to provide to my load 0.3 Amps). So, I'd prefer to use 5V power supply.
I need to use the same power supply for Arduino and my load for this project.
Can somebody tell me what I do wrong and what I should change or add in my circuit? Which resistors (R1;R3) values should I use?
I can't provide too much data of my device because it is confidential.
Of course it is!
Simplest way to do this is to abandon this circuit and use one output of a DC motor driver.
You can continue to struggle with this circuit, but you're going to need a gate drive and by the time you have assembled everything, you're well past the $3 for a 6612 or L298 motor drive that has far more current capability than you need.
I've just checked how I can draw inspiration from this.
Unfortunately your solution doesn't meet my needs very well, unless a single chip driver is used instead of printed boards.
I am aware that I could spend more and that won't be easy but, as previously mentioned, the type of circuit is the closest to what I need.
I say this based on research and trials I've done over the last few months.
I ask for help in improving and making this or something very similar work.
This is due to the nature of my load which is not a motor.
[quote]The second problem is that my Arduino, when powered with 5V gives a peak of only 4.3V in the pwm pin,[/quote]I'm not sure how close to 5V you can get with a "light" load (A MOSFET gate takes almost no current). But it can fully-switch-on a logic-level MOSFET.
How are you measuring that? You can't measure PWM with a multimeter but if you write a digital high you can measure it.
An N-channel MOSFET won't work because you need Vgs to turn the MOSFET on and the Source will be at 5V (or whatever the supply voltage is) when on.
If you use P-channel MOSFET, positive on the gate turns it off, and zero volts turns it on. But your MOSFET voltage can't be more than 5V (without additional driver circuitry) because you need 0V Vgs to turn it off.
I'm measuring the PWM voltage with an oscilloscope...
I'm using the multimeter only to measure the current through my load.
That's what I've found on internet, but I don't know why this doesn't happen, unless I can increase the voltage that reaches the gate.
To do this do I have to reverse the code to have the same control I originally wanted? In my research I have found that P-MOS are not very suitable for this purpose, but since it is not my field I could be wrong....
Unfortunately I didn't study electronic engineering, so I had to start from the basics and also look for everything I didn't know...
Thanks to both of you for the really useful answers!
To the others I would like to say that working in research for the university everything becomes confidential. I have sought help in this forum because in previous posts I have seen people who are more prepared than the professionals I have already contacted.
Ok ok.
If that's the case, how to close the topic?
I don't want any problems or quarrels.
The question will remain unresolved, given that in any case I have obtained ideas for my research of a solution and not definitive solutions.
So thank you all.
Well, we are heartbroken! Have fun with your project.
But surely at a university, there must be some people who actually understand electronics theory and circuit design. Take their courses, if there are any. Or are you not even allowed to talk with them?
