Hi All
I have a 24V FAN, which has four wires. VCC,GND, PWM and TACT.
The FAN requires a voltage between 0-4.5-5V on PWM to vary its speed.
The FAN has an internal pullup on the PWM line to 4.5V, whereby if the PWM is not connected to anything, the FAN runs at the maximum speed as the voltage on PWM is about 4.5V.
My microcontroller is working on 3.3V. Therefore I would need to use either a MOSFET or transistor.
Is there a certain parameter I should keep in mind when selecting MOSFET or transistor for PWM?
At the moment, we are using the 2N3904 but found that we had to use an additional pull-up to 5V; otherwise, when the PWM varied, it was not adjusting FAN proportionally. It was as if the transistor was drawing more current from the PWM than supplied by the fan internal pullup. Maybe I am wrong.
Is there a 3 pin transistor or Mosfet which would be recommended?
I have a 24V FAN, which has four wires. VCC,GND, PWM and TACT.
The FAN requires a voltage between 0-4.5-5V on PWM to vary its speed.
The FAN has an internal pullup on the PWM line to 4.5V, whereby if the PWM is not connected to anything, the FAN runs at the maximum speed as the voltage on PWM is about 4.5V.
My microcontroller is working on 3.3V. Therefore I would need to use either a MOSFET or transistor.
Is there a certain parameter I should keep in mind when selecting MOSFET or transistor for PWM?
At the moment, we are using the 2N3904 but found that we had to use an additional pull-up to 5V; otherwise, when the PWM varied, it was not adjusting FAN proportionally. It was as if the transistor was drawing more current from the PWM than supplied by the fan internal pullup. Maybe I am wrong.
Is there a 3 pin transistor or Mosfet which would be recommended?