Fixed Inductors

Part Number	Description / PDF	Quantity
ELL-4LG680MA Panasonic	FIXED IND 68UH 350MA 1.3 OHM SMD	5256
ELJ-QF30NGF Panasonic	FIXED IND 30NH 190MA 1.3 OHM SMD	9291
ELJ-RF33NGFB Panasonic	FIXED IND 33NH 170MA 1.4 OHM SMD	13160
ELJ-FB221JF Panasonic	FIXED IND 220UH 85MA 13 OHM SMD	64779
ELL-6PG4R7N Panasonic	FIXED IND 4.7UH 1.75A 58 MOHM	402
ELL-4FG3R3NA Panasonic	FIXED IND 3.3UH 1.22A 110 MOHM	594
ELL-CTV2R7N Panasonic	FIXED IND 2.7UH 5.7A 7 MOHM SMD	1441
ETQ-P5M680YFM Panasonic	FIXED IND 66UH 2.3A 276.1 MOHM	1173
ETQ-P5LR50XFA Panasonic	FIXED IND 500NH 30A 0.8 MOHM SMD	675
ELT-5KT6R8MA Panasonic	FIXED IND 6.8UH 760MA 300 MOHM	3136
ELJ-QF4N7ZF Panasonic	FIXED IND 4.7NH 360MA 170 MOHM	7837
ELJ-PC1R5MF Panasonic	FIXED IND 1.5UH 435MA 550 MOHM	1689
ELL-5PM270M Panasonic	FIXED IND 27UH 550MA 230 MOHM	1774
ELJ-PB270KF Panasonic	FIXED IND 27UH 270MA 1.2 OHM SMD	1500
ELL-6UH680M Panasonic	FIXED IND 68UH 700MA 230 MOHM	0
ELJ-QE8N2JFA Panasonic	FIXED IND 8.2NH 490MA 170 MOHM	786
ELL-VFG330MC Panasonic	FIXED IND 33UH 330MA 1.16 OHM	3343
ELJ-QF3N6ZF Panasonic	FIXED IND 3.6NH 380MA 140 MOHM	16014
ELJ-QF24NJF Panasonic	FIXED IND 24NH 200MA 1 OHM SMD	18167
ELJ-NC33NKF Panasonic	FIXED IND 33NH 220MA 510 MOHM	3786

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