Fixed Inductors

Part Number	Description / PDF	Quantity
744778139 Würth Elektronik Midcom	FIXED IND 39UH 1.03A 320 MOHM	0
7447789247W Würth Elektronik Midcom	FIXED IND 470UH 270MA 4.18 OHM	0
744761122A Würth Elektronik Midcom	FIXED IND 22NH 700MA 220 MOHM	1106
744355047 Würth Elektronik Midcom	FIXED IND 470NH 26A 0.9 MOHM SMD	410
744782039 Würth Elektronik Midcom	FIXED IND 3.9NH 300MA 450 MOHM	0
78438357082 Würth Elektronik Midcom	FIXED IND 8.2UH 2.8A 86MOHM SMD	339
744045120 Würth Elektronik Midcom	FIXED IND 12UH 800MA 420 MOHM	0
7443552430 Würth Elektronik Midcom	FIXED IND 4.3UH 8A 14.1 MOHM SMD	182
744775360 Würth Elektronik Midcom	FIXED IND 6MH 180MA 18 OHM SMD	477
74438366047 Würth Elektronik Midcom	FIXED IND 4.7UH 4.1A 63MOHM SMD	373
744304022 Würth Elektronik Midcom	FIXED IND 220NH 24A 0.17 MOHM	0
7443551111 Würth Elektronik Midcom	FIXED IND 11.3UH 11A 9.1 MOHM	3581
7443783533330 Würth Elektronik Midcom	FIXED IND 33UH 22A 9.9 MOHM TH	30
744766910 Würth Elektronik Midcom	FIXED IND 10UH 825MA 420 MOHM	439
750341595 Würth Elektronik Midcom	FIXED IND 700UH 1.329 OHM TH	0
7443082017 Würth Elektronik Midcom	FIXED IND 170NH 60A 0.18MOHM SMD	0
784776127 Würth Elektronik Midcom	FIXED IND 27UH 1.95A 110 MOHM	0
7447036 Würth Elektronik Midcom	FIXED IND 220UH 800MA 220 MOHM	332
7447789215 Würth Elektronik Midcom	FIXED IND 150UH 560MA 1.27 OHM	2890
7447720180 Würth Elektronik Midcom	FIXED IND 18UH 3.1A 47 MOHM TH	150

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