I have on hand a simple 12V/350mA stepper motor
the datasheet is lacking, so I can only assume 12V is the maximum sustained voltage and 350mA is again, the maximum associated current. The datasheet also lists the winding resistances as 35 Ohms, which I have verified.
What I found is that while driving the stepper at a rate of about 0.5 revolutions per second that it would draw 350mA at 12V. However, if I were to decrease or increase the speed of rotation, the motor would draw more or less current, respectively. Why is this? I am planning on testing this later today, but is it then necessary to drive the motor at a lower voltage to abide by the current constraints?
In summary for 12V supply:
0.25 rev/sec => 450mA
0.5 rev/sec => 350mA
3 rev/sec => 150mA