How to Use BLDC Brushless Fan Motor 5 inch: Examples, Pinouts, and Specs

The 5-inch Brushless Direct Current (BLDC) Fan Motor is a highly efficient and durable motor designed for cooling applications. Unlike traditional brushed motors, this BLDC motor operates without brushes, resulting in reduced wear and tear, quieter operation, and a longer lifespan. Its compact size and high performance make it ideal for use in electronics cooling, household appliances, and industrial equipment.

• Cooling systems for computers, servers, and other electronics
• Ventilation in household appliances such as air purifiers and refrigerators
• Industrial equipment requiring efficient airflow
• Automotive applications, including HVAC systems

1. Power Supply: Connect the VCC pin to a DC power source within the operating voltage range (12V to 24V). Ensure the power supply can provide sufficient current for the motor's operation.
2. Ground Connection: Connect the GND pin to the ground of the power supply and the circuit.
3. Speed Control: Use a PWM signal (typically 25 kHz) on the PWM Input pin to control the motor speed. A 0% duty cycle stops the motor, while a 100% duty cycle runs it at maximum speed.
4. Speed Monitoring: Connect the Tach Output pin to a microcontroller or monitoring device to measure the motor's RPM. Each pulse corresponds to a specific number of rotations.

• Voltage Compatibility: Ensure the power supply voltage matches the motor's operating range to avoid damage.
• PWM Signal: Use a stable PWM signal for precise speed control. Avoid abrupt changes in duty cycle to prevent motor stress.
• Cooling: While the motor is efficient, ensure adequate ventilation around it to maintain optimal performance.
• Polarity: Double-check the polarity of the power connections to prevent damage to the motor.

Below is an example of how to control the BLDC fan motor using an Arduino UNO:

// Example code to control a 5-inch BLDC fan motor using PWM on Arduino UNO

const int pwmPin = 9; // PWM output pin connected to the motor's PWM Input pin
const int tachPin = 2; // Tachometer input pin connected to the motor's Tach Output pin

volatile int tachCount = 0; // Variable to store tachometer pulse count

void setup() {
  pinMode(pwmPin, OUTPUT); // Set PWM pin as output
  pinMode(tachPin, INPUT_PULLUP); // Set Tach pin as input with pull-up resistor

  // Attach interrupt to count tachometer pulses
  attachInterrupt(digitalPinToInterrupt(tachPin), countTachPulses, FALLING);

  Serial.begin(9600); // Initialize serial communication for debugging
}

void loop() {
  // Set motor speed using PWM (0 to 255 corresponds to 0% to 100% duty cycle)
  analogWrite(pwmPin, 128); // 50% duty cycle for medium speed

  // Calculate RPM based on tachometer pulses
  int rpm = calculateRPM();
  Serial.print("Motor RPM: ");
  Serial.println(rpm);

  delay(1000); // Wait for 1 second before updating RPM
}

// Interrupt service routine to count tachometer pulses
void countTachPulses() {
  tachCount++;
}

// Function to calculate RPM based on tachometer pulses
int calculateRPM() {
  noInterrupts(); // Disable interrupts to read tachCount safely
  int pulses = tachCount;
  tachCount = 0; // Reset pulse count
  interrupts(); // Re-enable interrupts

  // Assuming 2 pulses per revolution, calculate RPM
  return (pulses * 60) / 2;
}

• Adjust the analogWrite value to control the motor speed.
• Ensure the tachometer pulse count matches the motor's specifications (e.g., 2 pulses per revolution).

1. Motor Does Not Start:

   • Cause: Incorrect power supply voltage or insufficient current.
   • Solution: Verify the power supply voltage and current rating. Ensure proper connections.

2. Motor Runs Erratically:

   • Cause: Unstable PWM signal or noise in the circuit.
   • Solution: Use a stable PWM source and ensure proper grounding.

3. No Tachometer Output:

   • Cause: Incorrect connection or damaged tachometer pin.
   • Solution: Check the connection to the Tach Output pin. Test with a multimeter or oscilloscope.

4. Overheating:

   • Cause: Prolonged operation at high speed without adequate ventilation.
   • Solution: Ensure proper airflow around the motor and reduce speed if necessary.

• Q: Can I run the motor without a PWM signal?

  • A: Yes, the motor will run at full speed if the PWM Input pin is left unconnected or set to 100% duty cycle.

• Q: What is the maximum cable length for the PWM signal?

  • A: For reliable operation, keep the PWM signal cable length under 1 meter. Use shielded cables for longer distances.

• Q: Can I use this motor with a 5V power supply?

  • A: No, the motor requires a minimum of 12V DC to operate.

• Q: How do I clean the motor?

  • A: Use compressed air to remove dust. Avoid using liquids or solvents that may damage internal components.