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MOSFET (Si/SiC) Forum Discussions

PatrickEganland
Level 1
5 questions asked 5 sign-ins First reply posted
Level 1

Hi

I have a bit of a problem that in hoping someone can shed some light on.

I have a 4 wire fan (from a power mac g5) and I found that the pinout is positive, negative, PWM and rpm output. It's a bit strange in that the 12v must be connected constantly and the fan speed is actually controlled with either a variable voltage to the PWM pin or I'm guessing an actual PWM of 12v would be more likely. I have tested this with 12, 5 and 3v to the PWM input and it works.

So what I am trying to do is control 4 of these fans with an arduino uno.

If I take a 12v wall wart and power the 12v rail on the fan, then use a mosfet to produce the 12v PWM signal using the arduino to drive the PWM input on the fan, is this the way to go? Can anyone show me an example of how to do this using 1 12v PSU?

My knowledge of transistors/mosfets azar echatspin is nil!

Thanks,

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1 Solution
Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @PatrickEganland ,

Thank you for posting on Infineon Community. 

Yes. You can use a transistor or MOSFET to apply the PWM signal based on the control input from Arduino.  Below shown image is a generic example of driving four fans from a single power supply unit. 

Meghana_0-1650387677051.png

It is important to note that the pwm applied to the fan and the input from Arduino are complimentary in above solution. It is also possible to apply PWM input which is in phase with the Arduino output using p channel MOSFETs, but we would then require additional supply voltage which will be same as supply voltage of Arduino. NPN transistors can also be used in place of MOSFETs for this application. 

To recommend appropriate MOSFET for this application we request below information.  

1. Do you want to control each fan independently or in parallel?  

2. Is the datasheet of the fan available? If so please share it. 

Kindly share us the details to suggest optimal solution. 

Regards

Meghana 

View solution in original post

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1 Reply
Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @PatrickEganland ,

Thank you for posting on Infineon Community. 

Yes. You can use a transistor or MOSFET to apply the PWM signal based on the control input from Arduino.  Below shown image is a generic example of driving four fans from a single power supply unit. 

Meghana_0-1650387677051.png

It is important to note that the pwm applied to the fan and the input from Arduino are complimentary in above solution. It is also possible to apply PWM input which is in phase with the Arduino output using p channel MOSFETs, but we would then require additional supply voltage which will be same as supply voltage of Arduino. NPN transistors can also be used in place of MOSFETs for this application. 

To recommend appropriate MOSFET for this application we request below information.  

1. Do you want to control each fan independently or in parallel?  

2. Is the datasheet of the fan available? If so please share it. 

Kindly share us the details to suggest optimal solution. 

Regards

Meghana 

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