Inductors:
Coils & chokes for
the highest demands
Precise and reliable passive components are essential in modern electronics – such as electromagnetic coils, chokes, and related inductors, which play a key role in countless applications, from power supply and signal filtering to high-frequency technology.
alfatec GmbH & Co. KG is your experienced partner and distributor for high-quality inductive components. In addition to a broad portfolio of leading manufacturers of transformers and coils such as Sunlord, we also offer in-depth technical expertise and individual consultation to find the perfect solution for your specific requirements.
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What are inductors? A technical overview
Inductors - often referred to as coils or chokes—are passive electronic components that store energy in a magnetic field when electric current flows through them (current flow). This principle is based on electromagnetic induction. The key parameter is inductance (L), which is measured in henries (H).
- Basic principle: A conductor, usually in the form of coils wound around a core, generates a magnetic field. Changes in the current flow induce a counter-voltage (induction voltage) that counteracts the change in current (Lenz's law). The number of coils (number of turns, N) determines the level of inductance.
Core materials: Different core materials are used depending on the application. Air coils do not have a ferromagnetic core and are well suited for high-frequency applications with low losses. Cores made of ferrite or iron powder are used for higher inductance values and to concentrate the magnetic field – they are often referred to simply as iron cores, although ferrite is ceramic. The core material influences saturation behavior, frequency range, and losses.
Types of inductors: The term covers various components:
- Coils (inductors): General term for inductive components used for energy storage, filtering, or as part of oscillating circuits.
- Chokes: Used specifically to suppress or limit alternating currents or high-frequency interference. They “choke” unwanted frequency components.
- Transformers: Consist of at least two coils on a common core and are used for voltage conversion or galvanic isolation. Although related, our focus here is primarily on inductors and chokes.
Focus on technical parameters
The following technical parameters are decisive for selecting the right induction coil or choke coil:
- Inductance (L): The nominal value, usually with a tolerance specification, such as ±10%.
- Direct current resistance (DCR): The ohmic resistance of the winding. Affects losses and self-heating. A low DCR is often desirable.
- Rated current (Irated): Maximum permissible direct current, which is typically limited by self-heating.
- Saturation current (Isat): The current at which the inductance drops significantly—by around 30%—due to core saturation. Important for power applications.
- Quality factor (Q): Measure of efficiency at a given frequency (ratio of reactive resistance to effective resistance). Important for RF and resonance applications.
- Self-resonant frequency (SRF): The frequency at which the inductance forms a resonant circuit with its parasitic capacitance. Above the SRF, the component behaves capacitively.
Product categories
alfatec portfolio: High-performance inductors from Sunlord
As your reliable distributor, we rely on strong partners. Sunlord is a leading global manufacturer of passive components, known for innovation, quality, and its extremely broad portfolio. alfatec offers you a wide range of Sunlord coils and chokes, including:
Power inductors:
- Function: Energy storage in DC/DC converters and switching power supplies (SMPS). Smoothing of output currents.
- Types available from Sunlord: Shielded/unshielded SMD power inductors, high-current inductors, molded chokes.
- Special features: High saturation currents, low DC resistance (DCR), optimized for high efficiency.
Chip inductors:
- Function: Miniaturized inductors for filtering, impedance matching, and as part of oscillating circuits in space-critical applications (e.g., mobile devices, wearables).
- Types available from Sunlord: Multilayer chip inductors, wire-wound chip inductors.
- Special features: Very small designs (up to 01005), wide inductance spectrum, high quality factors (Q) for RF applications.
RF inductors:
- Function: Used in high-frequency circuits (MHz to GHz) for filtering, matching, and in oscillators.
- Types available from Sunlord: Ceramic chip inductors, wire-wound RF inductors.
- Special features: High quality factors (Q), high self-resonant frequencies (SRF), precise tolerances.
Common mode chokes:
- Function: Suppression of common mode interference (EMI) on data and power lines without affecting the useful signal.
- Types available from Sunlord: SMD common mode chokes for various interfaces (USB, HDMI, CAN) and power supplies.
- Special features: High common mode impedance over a wide frequency range, low differential attenuation.
- Transformers: Sunlord also offers specialized transformers, such as those for LAN interfaces or Power over Ethernet (PoE).
Our partners in the field of magnetics
Sunlord
Our partner Sunlord has been developing and producing chip-based electronic components such as EMC or RF components, coils, inductors and transformers since 2000. The company also offers development work for customised designs and has already received Tier 1 certifications for this.
Chemi-Con
As the world's largest manufacturer of aluminium electrolytic capacitors, Chemi-Con has been driving development in this field since 1931. The core product portfolio is supplemented by other innovative components such as tantalum electrolytic capacitors, film capacitors, supercapacitors and many more, so that the manufacturer is characterised by a wide range of standard and special types of high quality, reliability and performance.
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