How to choose the right MOSFET

Hello everyone I’m pretty new, but I’ve been having some problems. Currently I’m building a tethered ROV submersible that I control from my computer. I’m using an Arduino Atmega to control it as well. I have six bilge pump motors that control the direction of the ROV. I’m close to finished except for this one part. The Arduino I am using has a pulse width modulation option available, and I would like to be able to have MOSFET motor drivers to drive each of the bilge pumps. The problem is I don’t know which MOSFET to choose. The Arduino’s output is 5V and the bilge motors run on a 3A draw and 12 volts. I have tried to look up how to find out what to use, but whenever I try a site like digikey all the information is very confusing to me. Could anyone give me some guidance? any help is greatly appreciated.


There’s a lot more to implementing a good H-bridge design than just the MOSFETs, and since your post doesn’t seem to show awareness of any other issues, I strongly recommend that you consider an integrated motor driver such as the VNH2SP30. Especially for the kind of voltage and current you’re citing, there’s not much benefit to going with a discrete design. Is there a reason you want to do that?

- Jan

I’m just trying to minimize parts count and especially cost. Is the motor driver you have listed capable of running multiple motors? Also do you have somewhere that I could read more into MOSFETs and how they work if so that would be great.

Well, going with discrete MOSFETs is definitely not the way to minimize parts count. I don’t have a particular MOSFET site to recommend, but there’s got to be a lot of good information on the manufacturers’ web sites (IRF, Fairchild, On Semi, etc.).

Are you asking about running multiple motors on one channel? As long as the total current you draw is within what the motor driver can supply, it doesn’t matter how many separate motors you have connected.

- Jan

Each motor has its own channel which is why I imagined this to not be so complicated, but that actually helps a lot thank you for all your help.