August 2012
L010796
8
Reducing Output Current
Reducing the output current is accomplished automatically and occurs approximately 20mSec after the last
clock input has been received. The amount of current per phase in the reduction mode is approximately
70% of the set current. When the current reduction circuit is activated, the current reduction resistor is
paralleled with the current adjustment potentiometer. This lowers the total resistance value, and thus
lowers the per phase output current.
Determine Output Current
The output current for the motor used when microstepping is determined differently from that of
a full/half step unipolar driver. In the DPE25611, 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 DPE25611. 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).
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.
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 de
-
termine 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 cen-
ter tap floating) use the specified per phase (or unipolar) current rating to determine the current
setting potentiometer value.
July 2018
