Fixed Inductors

Part Number	Description / PDF	Quantity
74437346015 Würth Elektronik Midcom	FIXED IND 1.5UH 7.2A 15 MOHM SMD	2555
74437336056 Würth Elektronik Midcom	FIXED IND 5.6UH 3.3A 63 MOHM SMD	1959
744373360068 Würth Elektronik Midcom	FIXED IND 680NH 8A 12 MOHM SMD	0
744025002 Würth Elektronik Midcom	FIXED IND 2.2UH 1.8A 66 MOHM SMD	19364
744776133 Würth Elektronik Midcom	FIXED IND 33UH 1.78A 120 MOHM	1143
78438334047 Würth Elektronik Midcom	FIXED IND 4.7UH 1.1A 307.8 MOHM	0
744770247W Würth Elektronik Midcom	FIXED IND 470UH 900MA 980 MOHM	0
74478215 Würth Elektronik Midcom	FIXED IND 15NH 250MA 1.4 OHM SMD	0
74456168 Würth Elektronik Midcom	FIXED IND 68UH 1.6A 240 MOHM SMD	627
744765191GA Würth Elektronik Midcom	FIXED IND 91NH 120MA 2.3OHM SMD	2950
74479776247 Würth Elektronik Midcom	FIXED IND 4.7UH 1A 160 MOHM SMD	0
74404052039 Würth Elektronik Midcom	FIXED IND 3.9UH 2.4A 50.5 MOHM	1180
7447649133 Würth Elektronik Midcom	FIXED IND 33UH 320MA 3.64 OHM	933
74438357012 Würth Elektronik Midcom	FIXED IND 1.2UH 7A 15.5 MOHM SMD	766
74404032150 Würth Elektronik Midcom	FIXED IND 15UH 730MA 300 MOHM	774
7440690010 Würth Elektronik Midcom	FIXED IND 1UH 3.6A 26 MOHM SMD	0
74451168 Würth Elektronik Midcom	FIXED IND 68UH 400MA 290 MOHM	850
78438335047 Würth Elektronik Midcom	FIXED IND 4.7UH 1.5A 162 MOHM	938
7443556450 Würth Elektronik Midcom	FIXED IND 4.5UH 20.5A 3.4 MOHM	0
744778168 Würth Elektronik Midcom	FIXED IND 68UH 740MA 520 MOHM	571

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