Stepper motor driver Allegro’s A4988 DMOS Micro-stepping Driver with adjustable current limiting, overcurrent and overtemperature protection, and five different microstep resolutions (down to 1/16-step).
The driver requires a logic supply voltage (3 – 5.5 V) and a motor supply voltage (8 – 35 )V. It can deliver up to approximately 1 A per phase without a heat sink or forced air flow (it is rated for 2 A per coil with sufficient additional cooling).
This A4988 stepper driver is provided with heat sink to protect the board from overheating.
- Five different step resolutions: full-step, half-step, quarter-step, eighth-step, and sixteenth-step
- Adjustable current control lets you set the maximum current output with a potentiometer.
- Over-temperature thermal shutdown, under-voltage lockout, and crossover-current protection
- Short-to-ground and shorted-load protection
The driver requires a logic supply voltage (3 – 5.5 V) to be connected across the VDD and GND pins and a motor supply voltage (8 – 35 V) to be connected across VMOT and GND. The logic voltage can be supplied from an external source, such as that powering the logic of the rest of the system.
The resolution (step size) selector inputs (MS1, MS2, MS3) enable selection from the five step resolutions according to the table below.
Each pulse to the STEP input corresponds to one microstep of the stepper motor in the direction selected by the DIR pin. Note that the STEP and DIR pins are not pulled to any particular voltage internally, so you should not leave either of these pins floating in your application. If you just want rotation in a single direction, you can tie DIR directly to VCC or GND. For details about these power states, see the datasheet.
One way to set the current limit is to put the driver into full-step mode and to measure the current running through a single motor coil without clocking the STEP input. The measured current will be 0.7 times the current limit (since both coils are always on and limited to 70% of the current limit setting in full-step mode).