Fixed Inductors

Part Number	Description / PDF	Quantity
7440700150 Würth Elektronik Midcom	FIXED IND 15UH 1.65A 140 MOHM	136
74404042330 Würth Elektronik Midcom	FIXED IND 33UH 650MA 460 MOHM	6473
74404054681 Würth Elektronik Midcom	FIXED IND 680UH 250MA 3.98 OHM	1088
7687779221 Würth Elektronik Midcom	FIXED IND 220UH 560MA 1.3 OHM	651
7447713470 Würth Elektronik Midcom	FIXED IND 47UH 1.2A 248 MOHM SMD	149
744750230068 Würth Elektronik Midcom	FIXED IND 6.8UH 5.7A 16 MOHM TH	265
7447714330 Würth Elektronik Midcom	FIXED IND 33UH 2.5A 79 MOHM SMD	2335
744710615 Würth Elektronik Midcom	FIXED IND 6UH 15A 3.5 MOHM TH	12
744028004 Würth Elektronik Midcom	FIXED IND 4.7UH 850MA 310 MOHM	8
7447773010 Würth Elektronik Midcom	FIXED IND 1UH 6A 12 MOHM SMD	975
744762210A Würth Elektronik Midcom	FIXED IND 100NH 1A 180 MOHM SMD	2052
744773022 Würth Elektronik Midcom	FIXED IND 2.2UH 2.5A 71 MOHM SMD	2905
744765111A Würth Elektronik Midcom	FIXED IND 11NH 640MA 120 MOHM	14515
74404031027A Würth Elektronik Midcom	FIXED IND 2.7UH 1.85A 80 MOHM	6513
784774118 Würth Elektronik Midcom	FIXED IND 18UH 1.45A 150 MOHM	0
74404063102 Würth Elektronik Midcom	FIXED IND 1MH 220MA 6.44 OHM SMD	954
7444211415100 Würth Elektronik Midcom	FIXED IND 10UH 6.7A 9.2MOHM TH	38
744900019 Würth Elektronik Midcom	FIXED IND 1.9NH 200MA 550 MOHM	0
7445110 Würth Elektronik Midcom	FIXED IND 10UH 1A 75 MOHM SMD	8014
7843330560 Würth Elektronik Midcom	FIXED IND 5.6UH 9.2A 13MOHM 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