Fixed Inductors

Part Number	Description / PDF	Quantity
SDR0603-471KL J.W. Miller / Bourns	FIXED IND 470UH 150MA 4.55OHM SM	65568
RL895-331K-RC J.W. Miller / Bourns	FIXED IND 330UH 510MA 610MOHM TH	0
RL875S-103K-RC J.W. Miller / Bourns	FIXED IND 10MH 74MA 35 OHM TH	0
SRN2009T-R68M J.W. Miller / Bourns	FIXED IND 0.68UH 1.5A 55MOHM SMD	1995
CM453232-120JL J.W. Miller / Bourns	FIXED IND 12UH 225MA 2 OHM SMD	0
SRP1038AA-150M J.W. Miller / Bourns	IND,11X10X3.8MM,15UH20%,6.25A,SH	500
SRP4020TA-1R0M J.W. Miller / Bourns	FIXED IND 1UH 5A 27 MOHM SMD	15982
9250A-564-RC J.W. Miller / Bourns	FIXED IND 560UH 90MA 10.5 OHM TH	174
SRR5018-8R9Y J.W. Miller / Bourns	FIXED IND 8.9UH 1.25A 116MOHM SM	0
RL622-180K-RC J.W. Miller / Bourns	FIXED IND 18UH 2.2A 61 MOHM TH	2100
SDR0603-680KL J.W. Miller / Bourns	FIXED IND 68UH 440MA 720MOHM SMD	204
RL622-181K-RC J.W. Miller / Bourns	FIXED IND 180UH 690MA 580MOHM TH	0
SRP4020TA-8R2M J.W. Miller / Bourns	FIXED IND 8.2UH 2A 180 MOHM SMD	928
2100HT-181-V-RC J.W. Miller / Bourns	FIXED IND 180UH 3.1A 120 MOHM TH	0
8230-48-RC J.W. Miller / Bourns	FIXED IND 15UH 205MA 2.8 OHM TH	12
SRU5018-1R5Y J.W. Miller / Bourns	FIXED IND 1.5UH 2.5A 15.5MOHM SM	471
RLB0712-150KL J.W. Miller / Bourns	FIXED IND 15UH 900MA 90 MOHM TH	0
SRR7032-150M J.W. Miller / Bourns	FIXED IND 15UH 1.1A 95 MOHM SMD	0
SDR1307A-471K J.W. Miller / Bourns	FIXED IND 470UH 900MA 720MOHM SM	0
2000-150-H-RC J.W. Miller / Bourns	FIXED IND 15UH 4.7A 29 MOHM TH	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