Fixed Inductors

Part Number	Description / PDF	Quantity
744772047 Würth Elektronik Midcom	FIXED IND 4.7UH 4A 18 MOHM TH	71
7447789270 Würth Elektronik Midcom	FIXED IND 270UH 400MA 2.31 OHM	0
744732681 Würth Elektronik Midcom	FIXED IND 680UH 420MA 2.2 OHM TH	134
7443762504010 Würth Elektronik Midcom	FIXED IND 1UH 39A 0.95 MOHM TH	200
7447471472 Würth Elektronik Midcom	FIXED IND 4.7MH 250MA 7.7 OHM TH	104
744782018 Würth Elektronik Midcom	FIXED IND 1.8NH 300MA 220 MOHM	0
744045220 Würth Elektronik Midcom	FIXED IND 22UH 630MA 700 MOHM	35
744741221 Würth Elektronik Midcom	FIXED IND 220UH 660MA 1.5 OHM TH	1207
74479876168C Würth Elektronik Midcom	FIXED IND 680NH 1.8A 60 MOHM SMD	300
7447709150 Würth Elektronik Midcom	FIXED IND 15UH 6.5A 26 MOHM SMD	0
744761268A Würth Elektronik Midcom	FIXED IND 680NH 120MA 2.9OHM SMD	11246
744313220 Würth Elektronik Midcom	FIXED IND 2.2UH 14A 5.7 MOHM SMD	386
74434035010 Würth Elektronik Midcom	FIXED IND 100NH 29A 0.38 MOHM	1990
7447231471 Würth Elektronik Midcom	FIXED IND 470UH 1.2A 410 MOHM TH	28
744373580068 Würth Elektronik Midcom	FIXED IND 680NH 15A 3.22 MOHM	0
744775347 Würth Elektronik Midcom	FIXED IND 4.7MH 200MA 13.8 OHM	234
74476013C Würth Elektronik Midcom	FIXED IND 33NH 500MA 270 MOHM	3543
768772821 Würth Elektronik Midcom	FIXED IND 820UH 500MA 1.92 OHM	200
744031006 Würth Elektronik Midcom	FIXED IND 6.8UH 850MA 156 MOHM	2522
744765147A Würth Elektronik Midcom	FIXED IND 47NH 100MA 830 MOHM	1556

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