Fixed Inductors

Part Number	Description / PDF	Quantity
SRU8028-330Y J.W. Miller / Bourns	FIXED IND 33UH 1.3A 147 MOHM SMD	317
78F471J-TR-RC J.W. Miller / Bourns	FIXED IND 470UH 90MA 14 OHM TH	9095
RL822-821K-RC J.W. Miller / Bourns	FIXED IND 820UH 180MA 2.7 OHM TH	0
SDR1307-121KL J.W. Miller / Bourns	FIXED IND 120UH 1.8A 210MOHM SMD	512
FSR1013-103KL J.W. Miller / Bourns	FIXED IND 10MH 45MA 35 OHM TH	0
8230-00-RC J.W. Miller / Bourns	FIXED IND 150NH 1.1A 100 MOHM TH	0
CE201210-3N3J J.W. Miller / Bourns	FIXED IND 3.3NH 300MA 130MOHM SM	3500
SRU1048-1R5Y J.W. Miller / Bourns	FIXED IND 1.5UH 7A 4.3 MOHM SMD	598
RLB9012-121KL J.W. Miller / Bourns	FIXED IND 120UH 1.25A 320MOHM TH	285
RL187-122J-RC J.W. Miller / Bourns	FIXED IND 1.2MH 150MA 9 OHM TH	0
RL824-471K-RC J.W. Miller / Bourns	FIXED IND 470UH 480MA 620MOHM TH	0
SRR1210-561M J.W. Miller / Bourns	FIXED IND 560UH 1.1A 900MOHM SMD	588
CE201210-R33J J.W. Miller / Bourns	FIXED IND 330NH 300MA 1.4OHM SMD	3446
SRP1238A-6R8M J.W. Miller / Bourns	FIXED IND 6.8UH 9A 24 MOHM SMD	0
RL875S-152K-RC J.W. Miller / Bourns	FIXED IND 1.5MH 190MA 4.5 OHM TH	0
SRR1208-470YL J.W. Miller / Bourns	FIXED IND 47UH 2.2A 85 MOHM SMD	4395
CM453232-3R9JL J.W. Miller / Bourns	FIXED IND 3.9UH 330MA 900MOHM SM	0
1110-220K-RC J.W. Miller / Bourns	FIXED IND 22UH 5.5A 20 MOHM TH	171
SRR1260A-151K J.W. Miller / Bourns	FIXED IND 150UH 1.55A 260MOHM SM	0
CM322522-1R8JL J.W. Miller / Bourns	FIXED IND 1.8UH 200MA 820MOHM SM	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