I am powering a small sg90 servo motor (see datasheet) directly using a 12V battery and a simple circuit to step down the voltage to the appropriate one for the servo. I noticed the servo has some coil windings and I suppose I could model it as an RLC circuit.
My question is, how can I know if a flyback protection diode is needed in cases like this? The manufacturer does not seem to care about the inductance since there is no mention of it in the datasheet…
I've already make some brief tests such as a few 90 degree turns and everything went well so far so I guess it is not vital to put such a diode (at least with short usage periods) however I would like to get some enlightment on this topic.
Best Answer
No diode is needed, but you should put both some bulk capacitance and high frequency bypass capacitance across the power leads.
Keep in mind that this is a "hobby servo" motor. You are not driving the motor directly. You are sending signals to a controller in the same package as the motor, and that controller drives the motor. Therefore, you should try to provide reasonably clean power and clean signals, but your circuit isn't driving a motor.