Fixed Inductors

Part Number	Description / PDF	Quantity
744770247 Würth Elektronik Midcom	FIXED IND 470UH 900MA 980 MOHM	0
744071150 Würth Elektronik Midcom	FIXED IND 15UH 2.8A 55 MOHM SMD	890
7447649147 Würth Elektronik Midcom	FIXED IND 47UH 250MA 5.46 OHM	1024
74404024180 Würth Elektronik Midcom	FIXED IND 18UH 460MA 830 MOHM	1855
7443082022 Würth Elektronik Midcom	FIXED IND 220NH 60A 0.18MOHM SMD	3857
74478612 Würth Elektronik Midcom	FIXED IND 22NH 600MA 650 MOHM	0
74404041010 Würth Elektronik Midcom	FIXED IND 1UH 2.52A 41 MOHM SMD	0
784776218 Würth Elektronik Midcom	FIXED IND 180UH 760MA 630 MOHM	0
744776227 Würth Elektronik Midcom	FIXED IND 270UH 620MA 970 MOHM	0
74404084681 Würth Elektronik Midcom	FIXED IND 680UH 520MA 2.032 OHM	765
74435581000 Würth Elektronik Midcom	FIXED IND 10UH 21A 3.4 MOHM SMD	1215
7447840168 Würth Elektronik Midcom	FIXED IND 68NH 180MA 1.25 OHM	9900
74404054330 Würth Elektronik Midcom	FIXED IND 33UH 1.2A 188 MOHM SMD	3284
744916087 Würth Elektronik Midcom	FIXED IND 8.7NH 1.5A 65 MOHM SMD	0
74404063068 Würth Elektronik Midcom	FIXED IND 6.8UH 2.4A 47 MOHM SMD	2151
74451222 Würth Elektronik Midcom	FIXED IND 220UH 220MA 770 MOHM	864
74438367022 Würth Elektronik Midcom	FIXED IND 2.2UH 7.5A 16.1 MOHM	123
744778233 Würth Elektronik Midcom	FIXED IND 330UH 320MA 2.62 OHM	2973
744045391 Würth Elektronik Midcom	FIXED IND 390UH 110MA 13 OHM SMD	676
74408943022 Würth Elektronik Midcom	FIXED IND 2.2UH 3A 30 MOHM SMD	1339

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