http://www.diodes.com/datasheets/DRDC3105.pdf
Not sure what I should be looking for on the timing specs, but the worst number I see there is 800ns which I think means the switching speed can be faster than 1mhz.
Seems like a nice chip. Might have to be careful in motor selection even if it will work though. I notice one motor I just checked has a stall current of 2A. It would be bad if the part were to blow if the motor was prevented from turning.
It's more than fast enough but where did you get the 20khz PWM spec ? That's not an arduino PWM frequency so where is it from ?
What I don't understand, is how that device has an output saturation voltage of only 125-160 mV
raschemmel:
It's more than fast enough but where did you get the 20khz PWM spec ? That's not an arduino PWM frequency so where is it from ?
20khz is a typical PWM speed when controlling motors. It's fast enough that the PWM won't cause the motor to buzz at an audible frequency. While it's true that the default PWM speed on the Arduino is 490hz you can change a few registers to get much higher PWM speeds.
michinyon:
What I don't understand, is how that device has an output saturation voltage of only 125-160 mV
Its a superbeta transistor I reckon.
Most motor take more than 0.5A, note.
Also the power dissipation at 20kHz will depend on the switching losses,
not just the on resistance losses, so you might have to derate for that.