Stepper motor - How to choose a driver

Question

I want to know how can I choose stepper driver, once I have decided on the stepper motor that I wish to use.

This is how I understand it: If a motor can draw a current of say 0.5 amps and operates on 6.5 volts, I should choose a driver that's capable of providing at least 1.4 times more current than 0.5A. (Let me know if my understanding is correct). Also will I damage the motor by using a driver that itself works on voltage of 8-35V (voltage higher than that of motor)?

Let me know if my understanding is correct that if the stepper can provide more current it's good and will not damage the motor?

I conducted an experiment recently and used a L293D board to run a stepper taken out of DVD drive. I found the chip got way too hot (chip could provide current only of about 600mA), but motor was a little toy. I wonder where I went wrong. Perhaps the operating voltage of the driver was high (4.5V-32V). I did not have datasheet for the motor unfortunately. I need help with choosing driver so that I don't burn something and could succeed in building my own CNC.

I do not wish to go with kits that come from China and want to make informed decision. :-)

Thanks.

Answer 1

If the winding resistance is such that you generate the intended phase current by simply applying the rated voltage, then simple drivers like the L293D will be OK. It may well be, if you're unsure of the motors characteristics, or need to operate over a range of supply voltages that you need to either choose a driver that has some form of current limiting built in, or do that yourself externally. Something like the L297 can do this, and generate the signals needed for the output stage, or you can implement similar logic easily with separate components - a quad op-amp/comparator can do the same.