Fixed Inductors

Part Number	Description / PDF	Quantity
74404084120 Würth Elektronik Midcom	FIXED IND 12UH 2.8A 40 MOHM SMD	300
744764018 Würth Elektronik Midcom	FIXED IND 1.8UH 350MA 900 MOHM	0
744765116A Würth Elektronik Midcom	FIXED IND 16NH 560MA 220 MOHM	3913
744045102 Würth Elektronik Midcom	FIXED IND 1MH 70MA 30 OHM SMD	1228
74404042221 Würth Elektronik Midcom	FIXED IND 220UH 250MA 3.45 OHM	666
74404064120 Würth Elektronik Midcom	FIXED IND 12UH 2.2A 58 MOHM SMD	1252
7440329004 Würth Elektronik Midcom	FIXED IND 4.7UH 650MA 195 MOHM	0
7447706151 Würth Elektronik Midcom	FIXED IND 150UH 1.55A 200 MOHM	386
744777127 Würth Elektronik Midcom	FIXED IND 27UH 1.24A 150 MOHM	924
74439369047 Würth Elektronik Midcom	FIXED IND 4.7UH 13.5A 5.4 MOHM	2172
744066220 Würth Elektronik Midcom	FIXED IND 22UH 2.5A 75 MOHM SMD	2253
7447728215 Würth Elektronik Midcom	FIXED IND 820UH 360MA 1.56 OHM	66
744710210 Würth Elektronik Midcom	FIXED IND 2UH 10A 3.8 MOHM TH	125
74458304 Würth Elektronik Midcom	FIXED IND 4.7MH 400MA 4.8 OHM	262
744784147A Würth Elektronik Midcom	FIXED IND 47NH 200MA 1.1 OHM SMD	1297
7447797820 Würth Elektronik Midcom	FIXED IND 8.2UH 5.05A 28.6 MOHM	4626
744311470 Würth Elektronik Midcom	FIXED IND 4.7UH 6A 19.5 MOHM SMD	1556
744772103 Würth Elektronik Midcom	FIXED IND 10MH 140MA 24 OHM TH	9
78438356018 Würth Elektronik Midcom	FIXED IND 1.8UH 4.6A 24.5 MOHM	0
744916020 Würth Elektronik Midcom	FIXED IND 2NH 2.1A 38 MOHM SMD	0

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