MST-109 is a microstep stepper motor drive designed to be used with maximum supply voltage of 60V and a maximum current of 9A.

The drive is based on a DSP microcontroller and has built-in sophisticated options for stepper motors control. These options are, an advanced algorithm for managing the operation of the stepper motor at higher revolution speed, the selection of microsteps up to 1/256 (binary and decimally selection), then the selection of quiet operation when the stepper motor is not in operation. This makes it possible to make maximum use of the available torque of the stepper motor at higher speeds.

The selection of microsteps, as well as other operating mode options, is made using DIP switches with 8 positions, which are located on the drive board.

Setting the current of stepper motors in the range of 1.0–9.0 A is done using an external resistor.

Powerful MOSFET transistors in TO220 package are used to drive stepper motors.

Stepper motors are controlled via three lines, STEP, DIR and ENA (Enable). This means that already developed popular software such as: mikroCNC (free), Mach3, Mach4, LinuxCNC (free) and similar can be used for multi-axis control.

The MST-109 can be connected to a computer via any Audioms Automatika Ethernet, USB motion controller and also via an IO3-R3 breakout board that communicates with the computer via the LPT port.

A single power supply (from 22–60 V DC) is required to power the stepper motor drive. The drive has an additional circuit for stabilizing the voltage necessary to power the control electronics.

The drive has an automatic reduction of the current flowing through the windings of the stepper motor. If there is no signal on the STEP line for more than 1 s, the coils current will be decreased to 50% of the set value. This reduces unnecessary heating of stepper motors.

The built-in soft start enables the stepper motor 1s after the supply voltage arrives, which reduces the current shock when switching power on.

The microstep drive for stepper motors MST-109 has a built-in overvoltage protection that is activated when the supply voltage exceeds 65 VDC.

For currents above 4 A per stepper motor phase, it is necessary to place the drive on an additional heat sink.

pdfMST-109 User's manual


Image Gallery

Highlighted characteristics

  • New generation of microstep drive for stepper motors based on DSP microcontroller
  • Precise, sophisticated stepper motor current regulation that provides higher torque at higher rpm
  • True sinusoidal shape of the current profile, without distortion and crossover distortion, which leads to less variation of the torque during microstepping, less vibration, noise and less heating of the stepper motor
  • Auto decay mode, without artifacts of the current profile present in the older generation of drives, suppresses the distortion caused by slow decay when the current decreases and fast decay when the current increases through the windings of the stepper motor
  • Up to 1/256 microsteps, resulting in 51200 steps per revolution of a typical stepper motor, for fine motion control even at low stepper motor revolution speeds
  • Built-in soft start/pause

Technical specifications

Characteristics Description - Value
Microstep resolution 1/1, 1/2, 1/4, 1/5, 1/8, 1/10, 1/16, 1/20, 1/25, 1/32, 1/50, 1/64, 1/100, 1/128, 1/200 and 1/256 microsteps
Number of axis 1
Phase current 9A max
Current setting 1.0-9.0A (by external resistor)
Supply voltage 22-60VDC max, recommended up to 55 VDC
Input control interface opto-isolated STEP, DIR and ENA (enable) command lines
Input current 8.5mA at 5V (TTL)
Input signal width > 1 µs (recommended > 5 µs)
Dimensions  80mm x 105mm x 31mm
Weight ~170g

NOTE: Specifications are subject to change without notice


This video shows test of microstep driver MST-109 with Leadshine NEMA 34 stepper motor 86HS85 (4.9 A; 8.5 Nm - 1203 oz-in; 8 leads; dimensions 82 mm x 82 mm x 134 mm; weight 3.8 kg - 134 oz). Windings are connected in parallel. Control with USB-MC Motion Controller with USB-UIO1 breakout board and Microstep Stepper Motor Drive MST-109 with 1/16 microstep resolution selected and 6.9 A phase current. Supply voltage was 64 VDC. Maximum revolution speed is 4000 RPM.


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