regarding ULN driver which has its voltage specifications of output voltage 50v but a normal stepper motor can tolerate upto 12v but v use ULN driving stepper motor..how is this possible?
I thought all the ULN… were darlington array low side drivers. They can withstand a maximum voltage differential between their emitter and collector of 50V and an input up to 30V.
So again what's your question? 12 volts will work, if it's within tolerance. You just drive the ULN with 12V not 50... Total power might be a problem because the current will be reciprocally higher at the lower voltage for a similarly powered stepper. Watch the input voltage if it's over the rails you'll need specifics from the PDF.