Motor drivers - will these work?

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41

Yes, I am trying to learn as much as possible. That’s why I am asking so much here too.

I am still a little unsatisfied with one thing. You suggest me to buy the 40v boards. Only one is in stock. Would it be much of a problem for me when I buy the 30v ones? Would I even notice it?

I do have one board for my “fried controller box”, my ardumoto went up in smoke :smiley:

Thanks again :slight_smile:

42

I think he is talking about linear voltage regulators in TO-92 case. Something like this:

43

I never saw a direct reference from Pololu but, I believe the FET driver chip used on these boards is an Allegro A3941. Read this data sheet. there is a wealth of information on it. Pay attention to the many ways the h-bridge can be driven. They have some nice diagrams.
http://www.allegromicro.com/en/Products/Part_Numbers/3941/3941.pdf
The main reason I suggested a board with 40 volt FETs is that your planning on driving the board at 18 volts. When using high frequency PWM (10 - 15 khz) the switching transients stress the intrinsic diode of the FET. A 40 volt fet will handle these better at 18 volts. If driven by locked anti-phase this is less of an issue.(synchronous rectification) Also other motor controller manufactures tackle the switching transients by putting bidirectional TVS’s from the motor output to ground. If the TVS break down voltage is say 2 volts below the reverse break down of the FET then they will take the brunt of the transient and they are better able to handle them. So will the 30 volt fet board work? Yes but it will be stressed more than the 40 volt board. International Rectifier Corp has a lot of papers on fets. You may want to read those also. In particular the one on repetitive avalanche.

44

My DFRobot motor driver has a ST Microelectronics L298N bridge IC on it if you’re looking for parts.

International Rectifier make excellent FET’s in my opinion, and their datahseets are very good too.

45

I guess it will be the 40v FETS then.
Luckily the distributor ordered new ones. I hope they will arrive soon. :slight_smile:

I won’t be making my own H-bridge, I would like to buy one. It would cost too much time and effort. :stuck_out_tongue:

The 40v ones are even cheaper then the 30v ones :smiley:

So you advise these?
http://www.watterott.com/de/Motor-Steuerung-20A-IRF7842PBF-24v20