Fixed Inductors

Part Number	Description / PDF	Quantity
SDR0403-120ML J.W. Miller / Bourns	FIXED IND 12UH 1.05A 210MOHM SMD	18067
RLB0608-1R8ML J.W. Miller / Bourns	FIXED IND 1.8UH 880MA 220MOHM TH	0
SRR5018-3R0Y J.W. Miller / Bourns	FIXED IND 3UH 2.2A 45 MOHM SMD	0
1120-681K-RC J.W. Miller / Bourns	FIXED IND 680UH 1.6A 430 MOHM TH	0
SRP1038C-R15M J.W. Miller / Bourns	FIXED IND 150NH 45A 0.6 MOHM SMD	340
SRR4828A-3R9Y J.W. Miller / Bourns	FIXED IND 3.9UH 3.4A 47 MOHM SMD	966
CW161009A-72NJ J.W. Miller / Bourns	FIXED IND 72NH 400MA 490MOHM SMD	990
SRP2512-1R0M J.W. Miller / Bourns	FIXED IND 1UH 3.4A 49 MOHM SMD	10399
1110-221K-RC J.W. Miller / Bourns	FIXED IND 220UH 1.6A 240 MOHM TH	814
PM1812-681J-RC J.W. Miller / Bourns	FIXED IND 680UH 50MA 30 OHM SMD	791
5719-RC J.W. Miller / Bourns	FIXED IND 2.25MH 1.75A 920MOHM	0
PM0805-5N6M-RC J.W. Miller / Bourns	FIXED IND 5.6NH 600MA 80MOHM SMD	0
SRP0510-4R7K J.W. Miller / Bourns	FIXED IND 4.7UH 2.4A 151 MOHM	300
CW252016-33NJ J.W. Miller / Bourns	FIXED IND 33NH 600MA 160MOHM SMD	0
SRR0908-472YL J.W. Miller / Bourns	FIXED IND 4.7MH 120MA 12 OHM SMD	0
SRP3020C-1R0M J.W. Miller / Bourns	FIXED IND 1UH 5A 36 MOHM SMD	3115
SRN5040TA-680K J.W. Miller / Bourns	FIXED IND 68UH 800MA 400MOHM SMD	4
RLB0913-473K J.W. Miller / Bourns	FIXED IND 47MH 55MA 99 OHM TH	0
SRR1210A-681M J.W. Miller / Bourns	FIXED IND 680UH 1A 1.2 OHM SMD	59
SRP5015TA-R68M J.W. Miller / Bourns	FIXED IND 680NH 7A 16.2 MOHM SMD	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