Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Fan control using a FET, ideal freq?

Status
Not open for further replies.
Jos Brink

Jos Brink

Member level 3
Member level 3
Joined
Jan 28, 2004
Messages
64
Helped
9
Reputation
18
Reaction score
2
Trophy points
1,288
Activity points
577
Hi,

I want to contol a Fan (24V/5W) using a Fet. I'm generating pwm with a controller (5V).
can anyone tell me:

what is the ideal pwm freq for this
and do you now a fet for this kind of application?

Thnx alot!
 

I don't think there is an ideal frequency for pwm controlled fans ..
I would start with quite low, say below 50Hz, but if you hear any noise you should try different one ..
I assume that you are after N-channel mosfet, so the popular IRF540 (or similar) will be a good choice ..
Here is an example: **broken link removed**
Regards,
IanP
 

mm and do you know a fet which is capable of driving this load with only 5V as Vgs?

my fet is cookin at the moment! :D (atm i'm using a FQD2N50)

but the frecuency is much better now, (running @ 100Hz)..
 

This mosfet is completely unsuitable for driving a low-voltage fan ..
Look at its parameters:
Rds(on)=5.3Ω
Vds=500V
Vgs .. ( https://www.fairchildsemi.com/ds/FQ/FQD2N50.pdf )
To drive a fan at 24Vdc you should select a mosfet with Rds(on)<0.1Ω
That was the reason I suggested the IRF540 with Vgs>2V, but any low-ohm low-voltage MOSFET will be good for this job ..
Regards,
IanP
 

    Jos Brink

    Jos Brink

    Points: 2
    Helpful Answer Positive Rating
I recomend to use single chip switching power supply.
for example you can use LM2576-adj and put potentiometer to feedbak path. In this way you can change output voltage from 1.2 - 24 volts.

Regards
Davood Amerion
 

but how would you like to control that with a uC? with a digital potentiometer?
Thnx for your tip, I already finished my design

so topic may be closed.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top