Server fan driver

I bought a four-wire fan for a server. When I connected it to the power supply, I found that the wind was too strong, and the Dupont wire it was plugged into was also hot. I then planned to use the control panel to adjust the wind speed.

I expected to use a low-cost small chip like 15F104W, but I saw that there are other projects on the platform, especially the project of the big guy wzw666, which uses GP9101. GP9101 is a relatively integrated IC that directly outputs PWM, think of what you want. , simple and crude, using a 100K ohm adjustable resistor/potentiometer, you can control the duty cycle and have an emergency stop function. Very good. The disadvantage is that the 4.5V-5.5V power supply voltage is a bit narrow. It would be even better if it supports 3.3V. I guess it is a direct 5V fan without the need for an LDO to reduce the voltage.

In addition, this IC is difficult to buy. It costs 10+ on Taobao, or the cheaper one does not include free shipping, which is more than 10 yuan, which is really a bit expensive. I procured a 6 yuan Lichuang Mall shipping coupon before gritting my teeth and buying it.