Fixed Inductors

Part Number	Description / PDF	Quantity
ELJ-QF18NJF Panasonic	FIXED IND 18NH 240MA 700 MOHM	1432
ELJ-NC68NKF Panasonic	FIXED IND 68NH 190MA 680 MOHM	1343
ELJ-QF3N3ZF Panasonic	FIXED IND 3.3NH 400MA 120 MOHM	18473
ELJ-QF6N2DF Panasonic	FIXED IND 6.2NH 330MA 250 MOHM	15415
ELJ-FCR27MF Panasonic	FIXED IND 270NH 180MA 750 MOHM	5229
ELT-5KN127C Panasonic	FIXED IND 220UH 100MA 2.4 OHM	2263
ELC-18E391L Panasonic	FIXED IND 390UH 1.8A 120 MOHM TH	0
ELJ-FA820KF Panasonic	FIXED IND 82UH 60MA 10 OHM SMD	439
ELL-6RH150M Panasonic	FIXED IND 15UH 850MA 150 MOHM	1051
ETQ-P4M100KFN Panasonic	FIXED IND 10UH 5.2A 44.44 MOHM	0
ETQ-P5LR60XFA Panasonic	FIXED IND 600NH 27A 1.1 MOHM SMD	0
ELT-3KN104B Panasonic	FIXED IND 1MH 30MA 35 OHM SMD	0
ELJ-RF1N5DF Panasonic	FIXED IND 1.5NH 400MA 70 MOHM	99560
ELJ-QF36NJF Panasonic	FIXED IND 36NH 160MA 1.6 OHM SMD	15565
ELL-4LG4R7NA Panasonic	FIXED IND 4.7UH 1.3A 90 MOHM SMD	1418
ETQ-P5M3R3YFM Panasonic	FIXED IND 3.3UH 10.4A 13.09 MOHM	829
ELJ-EA3R3MF Panasonic	FIXED IND 3.3UH 270MA 120 MOHM	30070
ELT-3KN136B Panasonic	FIXED IND 2MH 20MA 55 OHM SMD	1675
ELL-ATV121M Panasonic	FIXED IND 120UH 840MA 190 MOHM	75
ELT-5KN131C Panasonic	FIXED IND 390UH 120MA 2.8 OHM	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