Using fet's for car blower (10a)

[skmdmasud]

Hi..
i am plannig to build a pwm uC based blower speed controller for my car which has a 5 point switch at the moment. I did my uC pwn coding which seems to be fine. I am having trouble selecting a FET which will be driven by the uC. My uC gives 0.625v stepping totaling to 8 steps to 5V. I selected 2 fets based on price and availability

1. IRFZ44N -- http://www.irf.com/product-info/datasheets/data/irfz44n.pdf
2. IRF540N -- http://www.irf.com/product-info/datasheets/data/irf540n.pdf

I dont understand whether they are N channel or P channel from the datasheet? also what is the Saturation V of the FETs ? I understand they can both handle 20V max in their gate which will be ok in my case and handle over 30A.

Good to see all new interface of electro-tech-online...great work

 

[Nigel Goodwin]

Hi..
i am plannig to build a pwm uC based blower speed controller for my car which has a 5 point switch at the moment. I did my uC pwn coding which seems to be fine. I am having trouble selecting a FET which will be driven by the uC. My uC gives 0.625v stepping totaling to 8 steps to 5V. I selected 2 fets based on price and availability

What do you mean by "0.625V stepping" - PWM outputs varying pulse widths, not voltages - and it's VERY important that the output device is fully switched ON and OFF, and not operating in a linear manner.

 

[skmdmasud]

What do you mean by "0.625V stepping" - PWM outputs varying pulse widths, not voltages - and it's VERY important that the output device is fully switched ON and OFF, and not operating in a linear manner.

Hi..
sorry i dont know the technical terms. By stepping i mean my high frequency to low frequency changing states. with the pwm at high frequency i get 0.625v when measures by a volt meter and as i decrease the frequency my V increases. If i connect a led its brightness increases when i change the PWM.