Stepper motor driver boards are providing the enough power and controlling signals to the stepper motor for proper working. The driver circuits will controlling the rotation of motor by the sequence provided through the coil. So in this article i’m sharing the ULN2003 IC based Stepper motor driver circuit and PCB Layout.
Stepper Motor Driver Circuit Diagram
Connection and Working
This is a stepper motor driver circuit using the ULN2003A Darlington transistor array. The ULN2003A is used here to drive a unipolar stepper motor, such as the 28BYJ-48, which typically has four coils. The circuit operates from a 5 to 12V DC power supply. The power is connected at the pins of J3. A 10µF capacitor is used for decoupling and filtering power supply noise.
The four input signals for motor control (IN1 to IN4) are fed into the ULN2003A via connector J1. The respective outputs (1C to 4C) on the right side of the ULN2003A are connected to the stepper motor coils through connector J4 connector. The connection is based on the color code (red, orange, yellow, purple, blue) to match the motor wires.
Each output line from the ULN2003A also drives an LED (A to D) in series with a 470Ω resistor, which acting as visual indicators for each coil activation. The COM pin of the ULN2003A is connected to VCC through a diode (not shown but typical in practical setups) or left as shown for flyback diode protection internally, while the E (GND) pin is grounded.
When the controller (e.g., Arduino or microcontroller) sends pulses to the input pins IN1–IN4, the ULN2003A sinks current through the respective outputs, energizing the stepper motor coils in sequence. This causes the rotor to turn step-by-step. The LED indicators light up according to the active coil, helping in debugging and verifying the stepping sequence visually. This simple and reliable circuit is ideal for interfacing stepper motors with low-current logic controllers.
PCB Layout
