29-07-2015, 08:48 PM
It should be OK, but "+1" for prototyping it first 
Any MOS-FET will be quick enough for this. The switching frequency doesn't need to be too high - anything above 10kHz will be fine, depending on your hearing! The switching time of the MOS-FET will be a tiny fraction of this - perhaps not even easily detectable. (If you go looking, use a resistive load - the inductance of the motor will dominate the observed wave shape).
Providing the MOS-FET is correctly driven into saturation when conducting, the R(DS-ON) parameter is the one that matters - this is the resistance between drain and source. This device is 0.1 ohms. With 2 amps flowing, that's 0.4 watts. In practice, it'll be less than that because you have to consider the duty-cycle of the waveform - if the MOS-FET is only conducting for 50% of the time, then the average current is halved, and the power dissipation is quartered.
One way to reduce the power loss in the MOS-FET is to pick one with a lower R(DS-ON). An oldie but goodie is the BUZ11, which is 0.04 ohms. For 2 amps continuous, the power would be 160mW. Last time I used one in anger, I used it to drive about 5 amps into some 12V halogen lamps. Without a heat sink, it ran warm, but was fine.
Try it and see, comfortable in the knowledge that the MOS-FET could be upgraded if needed. Even so, I'd definitely leave space for your small heat sink, just in case. Another tip - for these small-ish power demands, you can use the PCB as a heat sink - just leave a large area of copper leading away from the middle pin... It's obviously most effective with surface-mount devices, but it's "free" to try...
Looking forward to seeing the finished project - I only wish I could finish one of mine this decade
Any MOS-FET will be quick enough for this. The switching frequency doesn't need to be too high - anything above 10kHz will be fine, depending on your hearing! The switching time of the MOS-FET will be a tiny fraction of this - perhaps not even easily detectable. (If you go looking, use a resistive load - the inductance of the motor will dominate the observed wave shape).
Providing the MOS-FET is correctly driven into saturation when conducting, the R(DS-ON) parameter is the one that matters - this is the resistance between drain and source. This device is 0.1 ohms. With 2 amps flowing, that's 0.4 watts. In practice, it'll be less than that because you have to consider the duty-cycle of the waveform - if the MOS-FET is only conducting for 50% of the time, then the average current is halved, and the power dissipation is quartered.
One way to reduce the power loss in the MOS-FET is to pick one with a lower R(DS-ON). An oldie but goodie is the BUZ11, which is 0.04 ohms. For 2 amps continuous, the power would be 160mW. Last time I used one in anger, I used it to drive about 5 amps into some 12V halogen lamps. Without a heat sink, it ran warm, but was fine.
Try it and see, comfortable in the knowledge that the MOS-FET could be upgraded if needed. Even so, I'd definitely leave space for your small heat sink, just in case. Another tip - for these small-ish power demands, you can use the PCB as a heat sink - just leave a large area of copper leading away from the middle pin... It's obviously most effective with surface-mount devices, but it's "free" to try...
Looking forward to seeing the finished project - I only wish I could finish one of mine this decade
