9#L010185 June 2007
Step Motor Configurations
Step motors can be configured as 4, 6, or 8 leads. Each configuration requires different currents. Refer to
the lead configurations and the procedures to determine their output current.
WARNING! Step motors will run hot even when configured correctly. Damage may occur to the motor if a
higher than specified current is used. Most specified motor currents are maximum values. Care should be
taken to not exceed these ratings.
Determining Output Current
The output current used for the motor when microstepping is determined differently from that of a full/half
step unipolar driver. In the MBC10SI1, 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 configuration of
the motor. There is a current adjustment potentiometer used to set the output current of the MBC10SI1
This sets the peak output current of the sine/cosine waves. The specified motor current (which is the
unipolar value) is multiplied by a factor of 1.0, 1.4, or 2.0 depending on the motor configuration (series,
half-coil, or parallel).
6 Lead Motors
When configuring a 6 lead motor in a half-coil configuration (connected from one end of the coil to the
center tap), multiply the specified per phase (or unipolar) current rating by 1.4 to determine the current
setting potentiometer value. This configuration will provide more torque at higher speeds when compared
to the series configuration.
When configuring the motor in a series configuration (connected from end to end with the center tap
floating) use the specified per phase (or unipolar) current rating to determine the current setting potenti-
ometer value.
4 Lead Motors
Multiply the specified series motor current by 1.4 to determine the current adjustment potentiometer
value. 4 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.