Driving MOSFET from uCPU

[Pax Writer]

Hi experts

This is probably easy if you know the answer:
How do I drive an IRF3205 MOSFET with the output from an AVR processor (0-5V)?
Is there a specific driver-IC or something which would make my life easier, or do I have to make a driver circuit myself? Space is an issue, as I have to make the overall size of my circuit as small as possible.
Specific suggestions or simply pointers to freely available litterature are most welcome.

Thanks in advance.

 

[audioguru]

The IRF3205 Mosfet is spec'd with 10V from gate to source. Some will barely turn on with only the 5V from your microcontroller.
The Mosfet has a high input capacitance that needs high current to charge it quickly if the frequency is high.

We don't know if you use PWM and what is the PWM frequency.
If the switching is not frequent then just a transistor, 2 resistors and a 10V-12V supply is needed to be added.

 

[Ubergeek63]

Digi-Key - FAN3100CSXCT-ND (Fairchild Semiconductor - FAN3100CSX)

perhaps

 

[crutschow]

Depending upon your requrements, International Rectifier has a DirectFET line **broken link removed** that is designed to be driven by a 5V source.

 

[Ubergeek63]

looking at the spec of the FET he is talking about those don't stand a chance... 40A @ 500V or something like that as I recall.

 

[crutschow]

looking at the spec of the FET he is talking about those don't stand a chance... 40A @ 500V or something like that as I recall.

Depends upon how much of that FET capacity he's really using.

 

[Pax Writer]

Hi all

Thanks for your answers.
The MOSFET is for a simple motor switch system. Sometimes it will act simply as a manually triggered switch, but sometimes it will be run in PWM-mode, either from a 555-timer circuit or an AVR-circuit.
When in PWM-mode, the planned frequency will be in the range from 150Hz to 1kHz.

The motor is running on various batteries (yes, you guessed it, its a hobby application), which are typically from 8-12V. The current is typically 50-60A.
There may be more suitable FETs out there, but the IRF3205 is the most widespread one around here (Denmark), and the cheapest one which will accept the currents. I've looked at others, but this one is around 5DKK/pcs at 50pcs where other suitable candidates are typically 5-10DKK more expensive. Who knows why...

Also, this MOSFET has proven itself as very suitable for my applications, as there is plenty of headroom for "sh*t happens" when two are in parallel, so when its summer and the ambient temperature is 40 degrees C, the switches will still happily conduct.

Now I'll take a good look at the International Rectifier line suggested as well as the Digikey part.

If you have more suggestions, I would love to see them. Audioguru, your suggestion is noted, but I'm still also curious about finding a driver IC.

Thanks again

 

[Ubergeek63]

in that case I would suggest this one:
Digi-Key - IRL3502PBF-ND (International Rectifier - IRL3502PBF)
it costs less, has a lower Rdson, and is logic level.