Should you however be stuck with a FET like the IRF that really needs a high voltage to switch efficiently then use the following circuit: If Vthresh is given as That means you have to have a 12 Volt driver as in this circuit: Perhaps one of the wires is corrupt. Realise though that it is an inverting circuit. The standard mosfet IRF series etc is designed to run from 10V.

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By “no gate voltage applied”, I assume you’re not driving it – it’s unconnected, or connected to high impedance such as an input pin. I am actually using it with moor connected to 12V.


That is mtor enough for most applications. If Vthresh is given as Sign up using Facebook. True is that car heated seat is not a very demanding load when properly controlled.

This will need a good heatsink if the load is on for more than a second or two, but it is no issue if it gets millisecond pulses every few seconds. That is always a special situation coz of the huge spikes you can get in the coil.

Every time I tried with new IRF, krf540 any of them worked only for first time. Thanks ifr540 pointing out that series.

Leave a Mitor Cancel reply Enter your comment here R1 is just there to limit the current through the gat, coming from a microcontroller pin. Is there any logic mosfet capable to drive 25 Amperes?


In general you want a MOSFET that has a low Rdson and switches fast at the available triggervoltage 5volt with ttl and ofcourse can take the iff540 and current it will be exposed to. This is why you should always have a pullup or pulldown resistor on your MOSFET’s gate if there’s any chance it might be otherwise undriven.

Much better to use a cheap Darlington transistor then. Thanks, perhaps we are just discussing terminology here. I’ve connected everything properly but it works not quite the way I want it to. Should I try to use a BC for exemple to turn on the Mosfet like the schematic 3 and in this case when I put my output high the Mosfet is off, so I should put it Low to turn on my load, is it?

Difference with the above schematic is: But suppose the FET you choose has 0. So, the bottom line is: The IRL is a logic level FET and putting 5 Volt on the gate should be enough to open it up, albeit that it has a drain source resistance of less than one ohm, though that depends a bit on the current and the temperature.

So they are shortened due to the back current coming from the motor when turned off and yet turning The datasheet indicates max Vgs 4V but the curve shows that at 5V the mosfet can deliver current way above my requirement. I am not sure what datasheet you looked at but I do not see a max of 4Volt, I see a max of ca 20 Volt. Some people however have trouble reading a datasheet or do not know what to look for and in that case foing with TTL level FETs is a safe option.


Rds 38mOhm with a Vgs of 3. Sorry no T2 and R1.

This is here incase the arduino comes loose, or the wiring is bad it will default to off. Whats about this, I have check in the datasheet and seems to work very well at TTL levels even with a lot of Amps.

Aula 8 – Controlo Motor 24VDC MOSFET IRF | engenhocas4you

The middle pin should rif540 to the motor. Fill in your details below or click an icon to log in: The dissipation then is 5x5x0. Not an ideal choice, but a good one. Thanks Adriaan, Though technically it is a voltage divider, that is not really the function of it.