1992 Pololu 2128 Pololu NewCondition
Stepper Motor Driver A4988 Carrier - Black Edition diagonal view

Stepper Motor Driver A4988 Carrier - Black Edition


Product Code : 1992

In Stock Now : 30
Incl. Tax: £8.17 Excl. Tax: £6.81
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  • Stepper Motor Driver A4988 Carrier - Black Edition top view
  • Stepper Motor Driver A4988 Carrier - Black Edition shematic
  • Stepper Motor Driver A4988 Carrier - Black Edition diagonal view
  • Stepper Motor Driver A4988 Carrier - Black Edition with header
  • Stepper Motor Driver A4988 Carrier - Black Edition with coin
  • Stepper Motor Driver A4988 Carrier - Black Edition wiring diagram

The Black Edition A4988 stepper motor driver carrier is a higher-performance drop-in replacement for the original A4988 stepper motor driver carrier. It features a four-layer PCB for better thermal performance, allowing the A4988 microstepping bipolar stepper motor driver to deliver approximately 20% more current than the two-layer (green) version. Like the original carrier, the Black Edition offers adjustable current limiting, over-current and over-temperature protection, and five different microstep resolutions. It operates from 8 V to 35 V and can deliver up to 2 A per coil with sufficient additional cooling. This board ships with 0.1″ male header pins included but not soldered in.

Power connections

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. These supplies should have appropriate decoupling capacitors close to the board, and they should be capable of delivering the expected currents (peaks up to 4 A for the motor supply).

Step (and microstep) size

Stepper motors typically have a step size specification (e.g. 1.8° or 200 steps per revolution), which applies to full steps. A microstepping driver such as the A4988 allows higher resolutions by allowing intermediate step locations, which are achieved by energizing the coils with intermediate current levels. For instance, driving a motor in quarter-step mode will give the 200-step-per-revolution motor 800 microsteps per revolution by using four different current levels.

The resolution (step size) selector inputs (MS1, MS2, and MS3) enable selection from the five step resolutions according to the table below. MS1 and MS3 have internal 100kΩ pull-down resistors and MS2 has an internal 50kΩ pull-down resistor, so leaving these three microstep selection pins disconnected results in full-step mode. For the microstep modes to function correctly, the current limit must be set low enough (see below) so that current limiting gets engaged. Otherwise, the intermediate current levels will not be correctly maintained, and the motor will skip microsteps.


MS1 MS2 MS3 Microstep Resolution
Low Low Low Full step
High Low Low Half step
Low High Low Quarter step
High High Low Eighth step
High High High Sixteenth step


Control inputs

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. The chip has three different inputs for controlling its many power states: RST, SLP, and EN. For details about these power states, see the datasheet. Please note that the RST pin is floating; if you are not using the pin, you can connect it to the adjacent SLP pin on the PCB to bring it high and enable the board.

Note: Four, six, and eight-wire stepper motors can be driven by the A4988. Some unipolar stepper motors (e.g. those with six or eight leads) can be controlled by this driver as bipolar stepper motors. Unipolar motors with five leads cannot be used with this driver.

Note: This product can get hot enough to burn you long before the chip overheats. Take care when handling this product and other components connected to it.

Note: Measuring the current draw at the power supply will generally not provide an accurate measure of the coil current. Since the input voltage to the driver can be significantly higher than the coil voltage, the measured current on the power supply can be quite a bit lower than the coil current (the driver and coil basically act like a switching step-down power supply). Also, if the supply voltage is very high compared to what the motor needs to achieve the set current, the duty cycle will be very low, which also leads to significant differences between average and RMS currents.


  • Simple step and direction control interface
  • 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, which lets you use voltages above your stepper motor’s rated voltage to achieve higher step rates
  • Intelligent chopping control that automatically selects the correct current decay mode (fast decay or slow decay)
  • Over-temperature thermal shutdown, under-voltage lockout, and crossover-current protection
  • Short-to-ground and shorted-load protection
  • 4-layer, 2 oz copper PCB for improved heat dissipation
  • Exposed solderable ground pad below the driver IC on the bottom of the PCB


  • Minimum operating voltage: 8 V
  • Maximum operating voltage: 35 V
  • Continuous current per phase:1.2 A Without a heat sink or forced air flow
  • Maximum current per phase: 2 A With sufficient additional cooling
  • Minimum logic voltage: 3 V
  • Maximum logic voltage: 5.5 V
  • Microstep resolutions:full, 1/2, 1/4, 1/8, and 1/16
  • No reverse voltage protection
  • Size: 0.6″ × 0.8″
  • Weight: 1.5 g

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