STM32 4-Pin DC Fan Control: Single Timer Channel vs. Multiple Channels

durna · ‎2025-08-22

Hi,

I want to control a 4-pin DC fan (9RA1212P1K001). I need to run 3 identical fans at the same time and at the same speed. In this case, what is the difference between using 3 different channels of the same timer and connecting each to the PWM input of each fan, versus using only one channel of the timer and connecting the PWM pins of all 3 fans to that single channel?

I should note that I'm powering this DC fan with an external power supply, and there's a MOSFET (AO3400) between the STM32 board's PWM-generating pin and the fan.

BR

mƎALLEm · ‎2025-10-15

Hello,

As all fans are running at the same speed you can use only one channel to control all the fans so you save 2 GPIO pins.

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