How many device can be connected to arduino pwm pin?

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Hello everyone,

I'm a newcomer to electronics world and have a little project with a few question to ask. I want to control multiple pwm fan (6 fan) using arduino nano as an controller. The fan is 14cm, 12v, 0.12A Arctic P14 The arduino is just sending the pwm signal to the fan via d10 pin and thats all. The power of the fan is generated by external power supply, only the pwm pin connected to arduino. I have tested this by using 1 fan and it works just fine but my questions is:

  1. Can arduino safely sending the pwm signal to all those fan? The length of the wire is about 30cm (it's a standard pc fan wire)

  2. Is there any specific wiring diagram to do this?

  3. Is there any differences between this two wiring diagram? (In term of pwm signal connection or power connection) Lets say the 6 connector on the side is the connector of the fan

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  1. It is better to split the connection to several arduino pwm pin? (1 fan to 1 arduino pwm pin)

Thank you everyone and sorry for my bad english

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  1. 300cm would probably be OK for 1 fan. Whether you can control 6 fans depends on the input impedance of the fan's PWM input terminal. In other words the sum of the currents into the PWM inputs must be less than the maximum output current from the Nano PWM pin (20mA recommended).

  2. Your schematic on the left.

  3. The one on the right will have voltage drops between each fan so the signal will be slightly less for each successive fan input. Probably not much. The one on the left, each fan gets the same signal.

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I checked the link but I don't see any specs for the PWM connection...

If you have a multimeter you can measure the current into the fan's PWM connection at 100% PWM. The "absolute maximum" from an Arduino pin is 40mA with 20mA as the "recommended maximum".

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hey thanks for the response

Okay then, 30cm is good to go i think. I have emailed the manufacture support two days ago asking about the pwm spefication but still no reply. How do it? Can i use amperemeter connected to the arduino pwm pin and fan pwm pin connection?
Okay i also think the left schematic is absolutely better but the right one is easier :grinning:

Thanks!

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Yes there is no specification about the pwm signal. I have emailed the support 2 days ago but no reply. 20mA for each individual pin or the total of all pin? I mean if its 20mA for each pin, i can split the connection for each fan

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Hey, if anyone intersted in this topic, i have done the project and the result is 1 arduino pwm pin can only handle 3 fan. I have tried connecting 4 and 5 fan in single pin and the arduino become unstable. Sometimes its reset by itself, sometimes the function of my code just doesn't run and sometimes the red led in arduino turned on until i manually reset it. So i ended up splitting 6 fan to 2 pwm arduino pin and it works like charm.

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