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What is a Power Inductor?

Date: 2024-06-29

A power Inductors, also called an Inductors coil and choke Inductors, is a passive electronic
component consisting of wire round around a core of ferrite that includes an air gap that is used
to clean up the output from high frequency switch power supplies.

Selecting an Inductors is more complicated than just choosing the inductance value. To be
confident that the Inductors will perform in your circuit, there are other specifications that will
need to be considered. Power Inductorss can be categorized by the following factors:

• DC resistance
• Tolerance
• Package size
• Nominal inductance
• Packaging
• Shielding
• Maximum rated current

Inductors Construction and Operation

An Inductors is characterized by its’ form and materials. They are formed by using insulated
copper wires that are wound in a coil around a core material, commonly ferrite, making it a two
terminal passive Inductors. When the current flows through the wire, an electromagnetic field will
develop, and the EMF will generate depending on the rate of change of the magnetic flux.
Inductorss typically offer low magnetic radiation for low noise environments by storing energy in
its’ magnetic field.

In a circuit, power Inductorss operate as energy-storing devices. They store it in a magnetic field
when current flows through them during the circuits on time and can deliver that energy to the
load during its’ off time.

AC vs DC Currents

To understand the behaviors of the AC and DC to a power Inductors, Lenz Law needs to be
understood. Lenz Law describes the reaction when the direction of the current induced in a
conductor by a changing magnetic field creates a magnetic field that opposes the change that
produced it.

When AC flows through an Inductors, it disrupts the flow and is opposed by the Inductors by
increasing the reactance. According to Lenz Law, this creates a magnetic field in which the
intensity is determined by the frequency of the AC. The higher the frequency of the AC, the
higher the rate of change current and blocking effect from the Inductors.

A steady DC flowing through an Inductors produces a uniform magnetic field and the magnetic
flux remains constant. The steady DC produces zero current change. From this, there is no selfinduction or self-induced EMF therefore there was no voltage induced and the Inductors does not oppose the DC.

Inductance and Tolerance

Inductance is defined as the electromotive force of any electric circuit that is created as the
result of a changing current. Any power Inductors can oppose a change in current flow to
intentionally prevent signals with a higher frequency from passing, or choking off higher
frequencies, while allowing signals of lower frequency to continue. This property is why
Inductorss are commonly referred to as “chokes”.

Ripple voltage

is a term used to quantify the amount of AC voltage that still appears on DC voltage when the
converter converts the AC into DC.

A power Inductors that will be used for smoothing out the ripple current from the output of a
DC/DC power supply may be specified with a ±20% inductance tolerance. Tolerance is the
difference in the inductance value of an actual Inductors compared to the specified value in the
data sheet. Typically, tolerance is specified at room temperature while understanding that the
actual inductance will vary significantly across a wide temperature range.

Understanding the inductance change over the expected operating temperature range is critical
because depending on the application, specified tolerances will vary. 

Does Inductance Vary with Frequency?

Yes, inductance of an Inductors will increase when the frequency of the applied voltage
increases.
In a typical Inductors, the nominal inductance increases to a peak, incurs parasitic capacitance,
and becomes zero at the self-resonant frequency of the Inductors. Up to the resonance
frequency point, the inductance trait common in the Inductors is displayed, but beyond the
resonance frequency, the parasitic element becomes dominant.

Where are Inductorss Used in Everyday Life? A major detriment to proper function of modern electronics is the power source used. An unstable voltage, phase noise, and varying current are just some factors that can cause improper function or even failure. A ‘dirty’ power source can be mitigated. Inductorss are a way to remove voltage, spurious noise, and current fluctuations from power supplies. The primary function of a power Inductors is to ensure a clean, stable DC power supply. Applications for low DC resistance shielded Inductorss: 

• DC/DC line conditioning 
• AC/DC power supplies 
• Digital switch mode power supplies 
• Differential mode filtering 
• Signal line chokes 

Additional Inductors applications:
• RF tuning circuits 
• RFI elimination 
• Energy storage 
• Signal line chokes 
• Inductive sensors 
• Filters

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