
January 2013L010133
Step Motor Confi gurations
Step motors can be confi gured as 4, 6 or 8 leads. Each confi guration requires different currents. Refer
to the lead confi gurations and the procedures to determine their output current.
Determining Output Current
The Output current for a motor used with a bipolar driver is determined differently from that of a unipolar
driver. In the MBC15081, a sine/cosine output function is used in rotating the motor. The output current
for a given motor is determined by the motors current rating and the wiring confi guration of the motor.
There is a current adjustment potentiometer used to set the output current of the MBC15081. This sets the
peak output current of the sine/cosine waves. The specifi ed motor current (which is the unipolar value) is
multiplied by a factor of 1.0, 1.4, or 2.0 depending on the motor confi guration (series, half-coil, or parallel).
6 Lead Motors
Half-Coil Connection: When confi guring a 6 lead motor in half-coil (connected from one end of the coil
to the center tap), multiply the specifi ed per Phase (or unipolar) current rating by 1.4 to determine the
current setting potentiometer value. This confi guration will provide more torque at higher speeds when
compared to the series confi guration.
Series: When confi guring the motor is series (connected from end to end with the center tap fl oating) use
the specifi ed per Phase (or unipolar) current rating to determine the current setting potentiometer value.
8 Lead Motors
Series Connection: When confi guring the motor windings in series, use the per Phase (or unipolar) cur-
rent rating to determine the current setting potentiometer value.
Parallel Connection: When confi guring the motor windings in parallel, multiply the per Phase (or unipolar)
current rating by 2.0 to determine the current setting potentiometer value.
4 Lead Motors
Series Connection: Multiply the specifi ed series motor current by 1.4 to determine the current adjustment
potentiometer value. Four Lead Motors are usually rated with their appropriate series current, as opposed
to the Phase Current, which is the rating for 6 and 8 lead motors.
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