How to Use Inductor: Examples, Pinouts, and Specs

An inductor, also known as a coil or reactor, is a passive electronic component designed to resist changes in current. Inductors are characterized by their ability to store energy in a magnetic field when electrical current flows through them. They are commonly used in a variety of applications including power supplies, radio frequency circuits, and as filtering devices in audio electronics.

• LC Filters: In combination with capacitors to form LC filters for signal processing.
• Chokes: To block higher-frequency AC signals while passing DC or lower-frequency signals.
• Energy Storage: In switch-mode power supplies to store energy temporarily.
• Transformers: Paired with other inductors to form transformers for voltage step-up or step-down.
• Inductive Sensors: For proximity sensing and metal detection.
• EMI Suppression: To reduce electromagnetic interference in electronic circuits.

• Inductance (L): Measured in henries (H), indicates the amount of energy stored for a given current.
• Rated Current (I): The maximum current the inductor can carry without saturation.
• DC Resistance (DCR): The resistance of the wire winding, affecting power loss.
• Self-Resonant Frequency (SRF): The frequency at which the inductor behaves as a resonator.
• Quality Factor (Q): A dimensionless parameter that describes the inductor's efficiency.
• Saturation Current (Isat): The current at which the inductor's inductance begins to decrease significantly.
• Temperature Rating: The range of operating temperatures for the inductor.

Inductors typically have two terminals. Below is a table describing the pin configuration for a through-hole inductor:

Surface-mount inductors will have a similar two-terminal configuration but will be designed for soldering directly onto a printed circuit board.

1. Identify Inductance Value: Determine the required inductance for your application.
2. Circuit Placement: Connect the inductor in series with the circuit for current control or in parallel with a capacitor for filtering.
3. Orientation: Since inductors are non-polarized, they can be connected in either direction.
4. Soldering: For through-hole inductors, use a soldering iron to attach the leads to the PCB. For surface-mount types, use reflow soldering techniques.

• Avoid Saturation: Ensure the operating current is below the inductor's saturation current.
• Minimize Losses: Select an inductor with a low DC resistance to reduce power losses.
• Thermal Management: Be aware of the temperature rating and provide adequate cooling if necessary.
• Physical Placement: Keep inductors away from components sensitive to magnetic fields.

• Overheating: Caused by excessive current or a high DC resistance.
• Saturation: Occurs when the inductor is subjected to a current above its rated saturation current.
• Noise: Inductors can introduce electromagnetic noise into a circuit if not properly shielded.

• Check Current Levels: Ensure the current through the inductor does not exceed its rated current.
• Inspect for Physical Damage: Look for signs of overheating or damaged windings.
• Measure Inductance: Use an LCR meter to verify the inductance is within specifications.

Q: Can I replace an inductor with a higher inductance value? A: It depends on the application. In filters, a higher inductance will change the cutoff frequency. In power applications, it may affect the efficiency and regulation.

Q: What happens if an inductor is placed near another inductor or transformer? A: Magnetic coupling may occur, which can lead to unwanted interference between the components.

Q: How do I choose the right inductor for my application? A: Consider the required inductance, current rating, DC resistance, quality factor, and size constraints for your specific application.

Below is an example of how to use an inductor in a simple LC filter circuit with an Arduino UNO to filter a PWM signal.

// Define the PWM pin and frequency
const int pwmPin = 3; // PWM output pin
const int pwmFrequency = 490; // PWM frequency in Hz

void setup() {
  // Set the PWM pin as an output
  pinMode(pwmPin, OUTPUT);
  // Start the PWM signal
  analogWrite(pwmPin, 128); // Set a 50% duty cycle
}

void loop() {
  // The inductor in the LC filter circuit will smooth out the PWM signal.
  // No additional code is needed for the inductor itself.
  // The rest of the code would depend on the specific application.
}

Note: This code assumes that an inductor and a capacitor are already connected in the correct configuration on a breadboard or PCB to form an LC filter. The inductor does not require any direct interaction through code, as its behavior is purely electrical.