Digital Stepper Drive DM556T
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6
5.3.2 Parallel Connection
An 8 lead motor in a parallel configuration offers a more stable, but lower torque at lower speeds. But because of the
lower inductance, there will be higher torque at higher speeds. Multiply the phase (or unipolar) current rating by 1.96,
or the bipolar current rating by 1.4, to determine the peak output current.
Figure 8: 8-lead motor parallel connections
6. Power Supply Selection
The DM556T can power medium and small size stepping motors (frame size from NEMA23 to 34). To get good
driving performances, it is important to select supply voltage and output current properly. Generally speaking, supply
voltage determines the high speed performance of the motor, while output current determines the output torque of the
driven motor (particularly at lower speed). Higher supply voltage will allow higher motor speed to be achieved, at the
price of more noise and heating. If the motion speed requirement is low, it’s better to use lower supply voltage to
decrease noise, heating and improve reliability.
6.1 Regulated or Unregulated Power Supply
Both regulated and unregulated power supplies can be used to supply the drive. However, unregulated power supplies
are preferred due to their ability to withstand current surge and fast response for current change. In the case when only
normal switching power supplies are available, it is important to use “OVERSIZE” high current output rating power
supplies (for example, using a 4A power supply for 3A stepper motor) to avoid problems such as current clamp. On the
other hand, if unregulated supply is used, one may use a power supply of lower current rating than that of motor
(typically 50%
～
70% of motor current). The reason is that the drive draws current from the power supply capacitor of
the unregulated supply only during the ON duration of the PWM cycle, but not during the OFF duration. Therefore, the
average current withdrawn from power supply is considerably less than motor current. For example, two 3A motors
can be well supplied by one power supply of 4A rating.
6.2 Power Supply Sharing
Multiple DM556T drives can share one power supply to reduce cost, if that power supply has enough power capacity.
To avoid cross interference, connect each stepper drive directly to the shared power supply separately. To avoid cross
interference, DO NOT daisy-chain connect the power supply input pins of the Drivers. Instead connect them to power
supply separately.
6.3 Selecting Supply Voltage
The DM556T is designed to operate 20 - +50VDC voltage input. When selecting a power supply, besides
voltage from the power supply power line voltage fluctuation and back EMF voltage generated during motor
deceleration needs also to be taken into account. Ideally it is suggested to use a power supply with the output range of
