PWM Fan Control (15V, 15A) with Power MOSFET + Optocoupler

[shsn]

Hello,

I recently replaced a radiator fan on my car and the rating on the fan says 12V (10-15V max) and 6.5A continuous (15A peak). There is an ECU that can output PWM with varying duty cycle (5-20kHz) with up to 5A max. But I would like to implement an optocoupler to protect the output pin of the ECU. I have chosen IRF2804S-7P as it seem to have enough current handling capabilities with low Rds. But the Vgs(th) on datasheet says 2V min and 4V max. Does it mean I need a some sort of voltage regulator to drop battery's 12V to around 3V to fully turn on the FET?

Also is there an appropriate optocoupler that I could use?

Thank you.
Erik.

 

[kam1787]

Vgs is gate voltage to turn on the device. The V(BR)DSS is a min of 40V, so need to limit the supply voltage.

 

[shsn]

Hi, thank you for a reply. I assumed V(BR)DSS is the maximum voltage between drain and source before MOSFET fails. So supplying 9-15V to drain of IRF2804 would be ok? With gate voltage, I would need a device to have PWM voltage between 2 and 4V to meet the specification.