DM860I Full Digital Stepper Drive Manual
6
6. Power Supply Selection
The DM860I can match medium and small size stepping motors (frame size from NEMA24 to 34) made by
STEPPERONLINE or other motor manufactures around the world. To achieve 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.
Power Supply
When using regulated power supplies, it is important to have large current output rating to avoid problems like
current clamp, for example using 4A supply for 3A motor-drive operation. 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 Therefore, the average current withdrawn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.
Multiple Drives
It is recommended to have multiple drives to share one power supply to reduce cost, if the supply has enough capacity.
To avoid cross interference, DO NOT daisy-chain the power supply input pins of the drives. (Instead, please connect
them to power supply separately.)
Selecting Supply Voltage
The power MOSFETS inside the DM860I can actually operate within +20 ~ 80VDC, including power input
fluctuation and back EMF voltage generated by motor coils during motor shaft deceleration. Higher supply voltage can
increase motor torque at higher speeds, thus helpful for avoiding losing steps. However, higher voltage may cause
bigger motor vibration at lower speed, and it may also cause over-voltage protection or even drive damage. Therefore,
it is suggested to choose only sufficiently high supply voltage for intended applications, leaving room for power
fluctuation and back-EMF.
7. Selecting Microstep Resolution and Drive Output Current
This drive uses an 8-bit DIP switch to set microstep resolution, and motor operating current, as shown below:
Microstep Resolution Selection
Microstep resolution is set by SW5, 6, 7, 8 of the DIP switch as shown in the following table:
