SMD-MB450A Bipolar Microstep Stepper Motor Driver – 18–50VDC
SMD-MB450A Bipolar Microstep Stepper Motor Driver
Restore smooth and accurate axis movement in a compatible laser engraving or cutting machine with the MB450A stepper motor driver.
The MB450A receives pulse and direction commands from the machine controller and converts them into controlled electrical current for a connected stepper motor. This allows the motor to move the laser gantry or machine axis in small, repeatable steps.
Adjustable motor-current and pulse-per-revolution settings allow the driver to be matched to the machine’s stepper motor and motion-control configuration. Correct setup helps provide smooth movement, accurate positioning, proper torque, and controlled motor temperatures.
Key Features
- Bipolar microstep motor driver
- 18–50VDC power input
- Designed for compatible two-phase hybrid stepper motors
- Eight selectable motor-current settings
- Current range of 0.71–3.00A RMS
- Corresponding peak-current range of 1.00–4.20A
- Fifteen selectable pulse-per-revolution settings
- Resolution settings from 400 to 25,600 pulses per revolution
- Pulse, direction, and enable control inputs
- +5V control-signal terminals
- Four-terminal bipolar motor output
- Selectable half or full idle current
- Optically isolated control inputs
- Power and alarm status indicator
- Overvoltage, undervoltage, overcurrent, short-circuit, and over-temperature protection
- Integrated aluminum heat sink
- Removable terminal connectors included
Motor-Current Settings
DIP switches SW1 through SW3 control the motor output current.
The chart printed on the MB450A lists both peak and RMS current. Peak current is approximately 1.4 times the RMS current.
| Peak Current | RMS Current | SW1 | SW2 | SW3 |
|---|---|---|---|---|
| 1.00A | 0.71A | ON | ON | ON |
| 1.46A | 1.04A | OFF | ON | ON |
| 1.92A | 1.36A | ON | OFF | ON |
| 2.37A | 1.69A | OFF | OFF | ON |
| 2.84A | 2.03A | ON | ON | OFF |
| 3.32A | 2.36A | OFF | ON | OFF |
| 3.76A | 2.69A | ON | OFF | OFF |
| 4.20A | 3.00A | OFF | OFF | OFF |
The selected current must be appropriate for the connected motor.
A setting that is too low may cause weak movement, stalling, or missed steps. A setting that is too high may cause excessive motor and driver temperatures.
SW4 Idle-Current Setting
SW4 controls the holding-current mode used when the motor is stopped.
- SW4 OFF: Half current
- SW4 ON: Full current
The half-current setting helps reduce motor heat while the axis is not moving. A replacement driver should normally be configured to match the original driver unless the motor and machine requirements have been properly verified.
Pulse-Per-Revolution Settings
DIP switches SW5 through SW8 control the number of input pulses required for one complete motor revolution.
| Pulses per Revolution | SW5 | SW6 | SW7 | SW8 |
|---|---|---|---|---|
| 400 | OFF | ON | ON | ON |
| 800 | ON | OFF | ON | ON |
| 1,600 | OFF | OFF | ON | ON |
| 3,200 | ON | ON | OFF | ON |
| 6,400 | OFF | ON | OFF | ON |
| 12,800 | ON | OFF | OFF | ON |
| 25,600 | OFF | OFF | OFF | ON |
| 1,000 | ON | ON | ON | OFF |
| 2,000 | OFF | ON | ON | OFF |
| 4,000 | ON | OFF | ON | OFF |
| 5,000 | OFF | OFF | ON | OFF |
| 8,000 | ON | ON | OFF | OFF |
| 10,000 | OFF | ON | OFF | OFF |
| 20,000 | ON | OFF | OFF | OFF |
| 25,000 | OFF | OFF | OFF | OFF |
The replacement driver should normally use the same SW5 through SW8 positions as the original driver.
Changing the pulse-per-revolution setting without updating the machine controller can cause incorrect travel distances, inaccurate positioning, or changes in axis speed.
Control-Signal Terminals
The control terminals shown on the driver are:
- PUL+ (+5V): Positive pulse-signal terminal
- PUL− (PUL): Pulse-signal terminal
- DIR+ (+5V): Positive direction-signal terminal
- DIR− (DIR): Direction-signal terminal
- ENBL+ (+5V): Positive enable-signal terminal
- ENBL− (ENB): Enable-signal terminal
The enable connection may not be used in every machine configuration. Match the wiring to the original driver and machine controller.
Power and Motor Terminals
The power and motor terminals shown on the driver are:
- DC−: Negative DC power input
- DC+: Positive DC power input
- A+: Motor phase A positive
- A−: Motor phase A negative
- B+: Motor phase B positive
- B−: Motor phase B negative
The DC power supply must remain within the driver’s printed input range of 18–50VDC.
The motor wires must be connected as the correct A and B phase pairs. Incorrect phase wiring may cause vibration, rough movement, excessive noise, movement in the wrong direction, or failure to rotate.
Compatible four-, six-, or eight-wire stepper motors may be used when their windings are correctly configured for bipolar operation.
Product Specifications
- Rabbit Laser USA part number: SMD-MB450A
- Driver model: MB450A
- Manufacturer: Sumtor Elec
- Product type: Bipolar microstep motor driver
- Input voltage: 18–50VDC
- Motor type: Compatible two-phase hybrid stepper motor
- Current settings: Eight
- RMS current range: 0.71–3.00A
- Peak-current range: 1.00–4.20A
- Pulse-per-revolution settings: Fifteen
- Resolution range: 400–25,600 pulses per revolution
- Control inputs: Pulse, direction, and enable
- Control-signal voltage shown:+5V
- Signal isolation: Optical isolation
- Motor outputs: A+, A−, B+, and B−
- Power inputs: DC+ and DC−
- Idle-current selection: Half or full current
- Status indicator: Power and alarm
- DIP switches: SW1 through SW8
- Heat sink and terminal connectors: Included
Compatibility Notice
Stepper motor drivers that look similar may have different input voltages, output-current tables, pulse settings, control-signal requirements, terminal arrangements, and DIP-switch functions.
Before ordering, compare the following with the original driver:
- MB450A model number
- 18–50VDC input requirement
- Peak and RMS current ratings
- SW1 through SW4 positions
- Pulse-per-revolution setting
- SW5 through SW8 positions
- PUL, DIR, and ENBL terminal arrangement
- DC+ and DC− power connections
- Motor phase connections
- Physical size and mounting locations
Do not select a replacement based only on the enclosure shape or amperage rating.
Important Installation Information
Disconnect the laser machine from electrical power before inspecting or replacing the stepper motor driver.
Photograph and label every wire and DIP-switch position before removing the original driver. Copying the original switch settings is normally the safest starting point when installing a direct replacement.
Confirm the DC+ and DC− connections before applying power. Reversing the input polarity may immediately damage the driver.
Never connect or disconnect the stepper motor while the driver is powered. Doing so may damage the driver’s output circuitry.
Mount the driver securely with enough open space around the heat sink for heat to escape. Avoid installing it near excessive dust, moisture, oil mist, corrosive fumes, or other heat-producing components.
After installation, test the axis at a low speed before returning the machine to normal operation.
Troubleshooting a Motion Problem
Stepper-driver problems may cause symptoms such as:
- An axis that does not move
- A motor that vibrates without rotating
- Jerky or uneven movement
- Missed steps
- Incorrect positioning
- Movement in only one direction
- Excessive motor or driver heat
- An illuminated alarm indicator
- Intermittent axis operation
These symptoms do not always mean the driver has failed. Similar problems may be caused by incorrect DIP-switch settings, loose wiring, damaged motor cables, incorrect phase pairing, low power-supply voltage, mechanical binding, controller problems, or a damaged stepper motor.
Confirm Compatibility Before Ordering
Not sure whether the SMD-MB450A is correct for your laser machine? Contact Rabbit Laser USA with your machine model and clear photos of the original driver, wiring terminals, and DIP-switch positions. Our technical support team can help confirm compatibility before you order.