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Which MOSFET?

Sammyj

Postman
Joined
Dec 21, 2015
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I'm currently planning my first build, an unregulated series box and I think I just about have everything needed in my basket except for the MOSFET as I don't know which channel I need and why.
So to the electrical guru's, which one do I need and what is the difference between them? I've had a quick google but it doesn't mention anything about channels.
Also, do they both use the same resistors?

Thanks :)
 
Thanks @Jugg1es :)
@Huggett pm'd me letting me know it is an N channel I need, so it's ordered but if anyone can shed any light on the difference between them I would be grateful, just so I know for the future :P
 
IRLB3034PBF is the most commonly used mosfet. Is that the one you ordered?

An n-channel mosfet is typically used to switch the low side (negative end of load).

A p-channel mosfet is typically used to the switch the high side (positive side of a load).

RDS ON is the on state resistance of the mosfet. Ideally you would want it to be 2 milliohms (0.002 ohms) or less. Higher than that would result in excessive power dissipation (mosfet heating).

VGS TH is a voltage that when applied to the gate (basically a capacitor, it gets charged) the mosfet will BEGIN to start turning on. The voltage of your batteries need to be higher than the VGS TH value listed in the data sheet.

ID is the max current. The value may be quite high, several hundred amps. But note that is at 25C (about room temp). Due to the resistance of the mosfet (RDS ON) and the resulting power dissipation, without a heat sink the mosfet will be able to handle much less than that (observing thermal limitations). A 3034 without a heat sink is good for approximately 30 amps without overheating.

VGS will be the max voltage you can apply to the gate. Don't exceed what is listed.

I only mentioned a few of the different specs, but those are some of the most important ones for your purpose.

Would recommend you watch this great video on mosfets, goes into some functionality and detail on some of the specs:
 
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