Fixed Inductors

Part Number	Description / PDF	Quantity
7447480332 Würth Elektronik Midcom	FIXED IND 3.3MH 360MA 4 OHM TH	0
7843320100 Würth Elektronik Midcom	FIXED IND 1UH 22.5A 2.4MOHM SMD	0
744071221 Würth Elektronik Midcom	FIXED IND 220UH 720MA 610 MOHM	900
74478608 Würth Elektronik Midcom	FIXED IND 8.2NH 600MA 400 MOHM	0
744373680045 Würth Elektronik Midcom	FIXED IND 450NH 20A 1.5 MOHM SMD	0
74456082 Würth Elektronik Midcom	FIXED IND 8.2UH 3.2A 40 MOHM SMD	0
744071047 Würth Elektronik Midcom	FIXED IND 4.7UH 4.8A 22 MOHM SMD	210
744900033 Würth Elektronik Midcom	FIXED IND 3.3NH 150MA 1 OHM SMD	0
74404084180 Würth Elektronik Midcom	FIXED IND 18UH 2.4A 53 MOHM SMD	849
744784168A Würth Elektronik Midcom	FIXED IND 68NH 180MA 2.1 OHM SMD	0
744750530047 Würth Elektronik Midcom	FIXED IND 4.7UH 11.8A 4.8 MOHM	78
744762122A Würth Elektronik Midcom	FIXED IND 22NH 1A 100 MOHM SMD	2000
744373770022 Würth Elektronik Midcom	FIXED IND 220NH 25A 0.9 MOHM SMD	0
744765056A Würth Elektronik Midcom	FIXED IND 5.6NH 760MA 83 MOHM	11011
744309047 Würth Elektronik Midcom	FIXED IND 470NH 47.5A 0.165 MOHM	3830
7445610 Würth Elektronik Midcom	FIXED IND 10UH 3.3A 45 MOHM SMD	254
784776068 Würth Elektronik Midcom	FIXED IND 6.8UH 4.4A 19 MOHM SMD	0
744787121 Würth Elektronik Midcom	FIXED IND 120UH 730MA 643 MOHM	0
744766122 Würth Elektronik Midcom	FIXED IND 22UH 180MA 3.2 OHM SMD	1000
744042004 Würth Elektronik Midcom	FIXED IND 4.7UH 1.72A 82 MOHM	7019

Fixed Inductors

1. Overview

Fixed inductors are passive electronic components designed to store energy in magnetic fields when electrical current flows through them. Unlike variable inductors, their inductance values remain constant during operation. These components play critical roles in filtering, signal processing, energy storage, and electromagnetic interference (EMI) suppression across modern electronics, including power supplies, communication systems, and automotive electronics.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
Wirewound Inductors	High precision, high current handling, low resistance	Power supplies, DC-DC converters
Chip Inductors	Compact SMD package, stable performance at high frequencies	Mobile devices, RF circuits
Ferrite Bead Inductors	Effective high-frequency noise suppression	EMI filtering in digital circuits
Thin-Film Inductors	Ultra-compact, high Q-factor, tight tolerance	5G communication modules, IoT devices

3. Structure and Composition

Typical fixed inductors consist of:

Magnetic Core: Made from ferrite, powdered iron, or composite materials to concentrate magnetic flux
Coil Structure: Copper wire wound around the core (enamelled or silver-plated)
Encapsulation: Molded resin or ceramic coating for mechanical protection and insulation
Terminations: Solder-coated ends for PCB mounting (for SMD types) or leaded connections

4. Key Technical Specifications

Parameter	Description	Importance
Inductance (L)	Measured in henrys (H), determines energy storage capacity	Defines filtering/energy storage performance
Rated Current (I_rated)	Maximum DC current before saturation	Prevents core saturation and failure
DC Resistance (DCR)	Resistance of coil windings	Affects efficiency and thermal performance
Self-Resonant Frequency (SRF)	Frequency where inductor behaves as capacitor	Limits effective operating frequency range
Q Factor	Quality factor indicating efficiency	Higher Q = lower energy losses

5. Application Fields

Consumer Electronics: Smartphones, laptops, LED drivers
Industrial Equipment: Motor drives, power inverters
Automotive Systems: ECU modules, EV battery management
Telecom Infrastructure: Base station filters, optical transceivers

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Features
Murata	LQH3NPN100M	10 H, 1.2A, 1.8 1.4mm chip inductor
TDK	MLZ2012A100T	100MHz SRF, 1.0 1.25mm for RF circuits
Vishay	IHLP2525CZER1R0M	1 H, 12A, composite construction
Coilcraft	0402DC-103J	10 H, 5% tolerance, ultra-low profile

7. Selection Guidelines

Key considerations during selection:

Calculate required inductance based on switching frequency and ripple current
Verify rated current exceeds maximum operating current by 20-30%
Select SRF higher than circuit operating frequency
Consider package size vs. thermal dissipation requirements
For EMI suppression: Choose ferrite beads with impedance curves matching target frequencies

8. Industry Trends

Current development trends include:

Miniaturization: Sub-0.5mm size inductors for wearable devices
High-Frequency Operation: Components supporting >10GHz 5G applications
Integrated Solutions: Combined inductor-filter modules
Material Innovation: Nanocrystalline cores for higher saturation flux
Automotive Focus: AEC-Q qualified parts for EV/HEV systems