I’m completely puzzled by the following issue and I would be very interested in someone’s helping hand on this :
I developped a PCB on the basis of a Pro Mini (ATMEGA 328P 16Mhz 5V) and I added the capability to drive a 24V brushless DC FAN from Sanyo Denki (Ref 9GA0424P3J001).
I have a MOSFET (NXP PMV20EN) which gate pin is connected to a ATMEGA digital pin (non PWM).
I have a 150Ohm resistance in serie between the Arduino pin and the Gate pin.
I also have a 10K pulldown resistance at the gate pin.
There is also a diode in parallel of the FAN pins.
I have the following behavior which is strange :
Case 1 : When I set pin to HIGH, the FAN keeps on reacting for a moment (just as if it was starting running) and then stopping. When I measure the voltage on the Gate PIn, the value sways around 0V despite the HIGH value.
Case 2 : If I unplug the FAN and then I set the gate pin to HIGH : I normally get continous 5V.
And after several seconds, if I pulg the FAN back, the FAN works fine.
How come the fact that the FAN is plugged or not can change the behavior of the MOSFET?
Case 3 : while in case 1 or not, if I put external 5V to the gate pin, the FAN starts running fine.
Is anybody have an idea where the problem comes from?
Could it be related to the Gate capacitance or something? The MOSFET seems ok if we consider case 3… However seems to be more that there is something wrong in the relation between arduino pin and mosfet?
Thanks for your support