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I want to implement a driver circuit for a (sensored) motor that I am purchasing which has the characteristics (on the shopping website):

Max Amps: 16 Max Power: 350W ESC: 35A KV: 1900

The name/title of the motor contains the word: "17.5T"

What MOSFETs should I purchase? I see name/titles such as: "30V 60A", "12A 500V", "100V 5A", etc.

My current guess is to choose one >= 16A, however the ESC spec says 35A. I have even lesser confidence regaring the "V" of the MOSFET. The spec says max power: 350W, and I feel that simply dividing 350W/16A = ~22V might be too low. On the other hand I know that the power is dissipated over multiple MOSFETs (3 or 6?) in which case 22V might be overkill.

I did skim through various tutorials I found but they aren't in the context of the commercial specs of motors.

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    \$\begingroup\$ One that can safely pass 16A of current really. You also have to consider the voltage across the MOSFET with your design. Then just consider your worst case conditions where the MOSFET will see the most current through and voltage across its terminals and make sure that I*V is within the power spec. Also note that one MOSFET will only allow you drive the circuit in one direction. If you intend to drive the motor bidirectionally then consider an H-Bridge. \$\endgroup\$ – sherrellbc Jul 22 '14 at 1:35
  • \$\begingroup\$ @sherrellbc thanks. i guess that means i can ignore the part of its spec where it says ESC:35A. \$\endgroup\$ – necromancer Jul 22 '14 at 3:04
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In its intended application (1/10th scale RC car) that motor could draw over 30A when the vehicle is accelerating. For efficiency you want the FETs to have low voltage drop (<0.1V), so the most important parameter is RDson (at 35A it should be 0.0035 Ohms or less). As a result they may end up rated for much higher current than you need, which is good because then you won't need an enormous heat sink to keep them cool.

That motor is normally powered from a 7.4V or 11.1V battery. FETs rated at 30V should be fine so long as you stay below 26V.

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  • \$\begingroup\$ hey may end up rated for much higher current than you need, which is good because then you won't need an enormous heat sink to keep them cool The fact that a component is rated for high current doesn't necessarily mean it is able to dissipate a lot of power without a heatsink. \$\endgroup\$ – m.Alin Jul 22 '14 at 8:17

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