How to Use L293D: Examples, Pinouts, and Specs

The L293D is a dual H-bridge motor driver IC designed to control the direction and speed of DC motors and stepper motors. It is widely used in robotics and automation projects due to its ability to drive two motors simultaneously. Each channel of the L293D can handle up to 600 mA of current, making it suitable for small to medium-sized motors. The IC also features built-in diodes for back-EMF protection, ensuring safe operation with inductive loads like motors.

• Robotics: Driving wheels or robotic arms
• Automation: Conveyor belts, automated gates
• DIY projects: Remote-controlled cars, drones
• Stepper motor control for CNC machines or 3D printers

Below are the key technical details of the L293D motor driver IC:

The L293D comes in a 16-pin DIP (Dual Inline Package). Below is the pinout and description:

1. Power Connections:

   • Connect Vcc1 (Pin 16) to a 5V logic power supply.
   • Connect Vcc2 (Pin 8) to the motor power supply (4.5V to 36V, depending on the motor).
   • Connect all GND pins (Pins 4, 5, 12, 13) to the ground of the power supply.

2. Motor Connections:

   • Connect the motor terminals to the output pins (Output 1 and Output 2 for Motor 1, Output 3 and Output 4 for Motor 2).

3. Control Logic:

   • Use the input pins (Input 1, Input 2, Input 3, Input 4) to control the direction of the motors.
   • Enable the H-bridges by setting the Enable pins (Enable 1,2 and Enable 3,4) to HIGH.

4. Direction Control:

   • Set the input pins as follows to control motor direction:
     • Input 1 = HIGH, Input 2 = LOW → Motor 1 rotates forward.
     • Input 1 = LOW, Input 2 = HIGH → Motor 1 rotates backward.
     • Input 3 = HIGH, Input 4 = LOW → Motor 2 rotates forward.
     • Input 3 = LOW, Input 4 = HIGH → Motor 2 rotates backward.

5. Speed Control:

   • Use a PWM (Pulse Width Modulation) signal on the Enable pins to control motor speed.

Below is an example Arduino code to control a DC motor using the L293D:

// Define motor control pins
const int enablePin = 9;  // PWM pin for speed control
const int input1Pin = 7;  // Direction control pin 1
const int input2Pin = 8;  // Direction control pin 2

void setup() {
  // Set motor control pins as outputs
  pinMode(enablePin, OUTPUT);
  pinMode(input1Pin, OUTPUT);
  pinMode(input2Pin, OUTPUT);
}

void loop() {
  // Rotate motor forward at 50% speed
  analogWrite(enablePin, 128);  // Set speed (0-255)
  digitalWrite(input1Pin, HIGH); // Set direction
  digitalWrite(input2Pin, LOW);
  delay(2000); // Run for 2 seconds

  // Rotate motor backward at full speed
  analogWrite(enablePin, 255);  // Set speed (0-255)
  digitalWrite(input1Pin, LOW);  // Set direction
  digitalWrite(input2Pin, HIGH);
  delay(2000); // Run for 2 seconds

  // Stop the motor
  analogWrite(enablePin, 0);  // Set speed to 0
  delay(2000); // Wait for 2 seconds
}

• Ensure the motor power supply voltage matches the motor's specifications.
• Do not exceed the maximum current rating of 600 mA per channel.
• Use a heat sink if the IC gets too hot during operation.
• Always connect all ground pins to a common ground.

1. Motor Not Spinning:

   • Check if the Enable pin is set to HIGH.
   • Verify the motor power supply voltage and connections.
   • Ensure the input pins are configured correctly for the desired direction.

2. Motor Spins in the Wrong Direction:

   • Swap the logic levels of the input pins (e.g., HIGH to LOW and vice versa).

3. IC Overheating:

   • Ensure the current drawn by the motor does not exceed 600 mA per channel.
   • Use a heat sink or reduce the motor load.

4. No Response from the Motor:

   • Check the ground connections between the L293D, power supply, and microcontroller.
   • Verify that the logic power supply (Vcc1) is 5V.

Q: Can the L293D drive stepper motors?
A: Yes, the L293D can drive stepper motors by controlling the sequence of inputs to the H-bridges.

Q: Can I use the L293D with a 3.3V microcontroller?
A: The L293D requires a minimum logic voltage of 4.5V. Use a level shifter or a 5V microcontroller for compatibility.

Q: How do I control motor speed with the L293D?
A: Use a PWM signal on the Enable pins to adjust the motor speed.

Q: What happens if I exceed the current rating?
A: Exceeding the current rating can damage the IC. Use motors within the specified current limits or add external current-limiting circuitry.